M§mm

, it J '■*■■■ '.s)i /Mi> 1 »/ 'AH* /^*^ -i !

-Wfi

•iKHlfevf

0 'I-; f^

%

THE FAMILIES AND GENERA OF LIVING RODENTS

BRITISH MUSEUM (NATURAL HISTORY)

THE FAMILIES AND GENERA

OF

LIVING RODENTS

^ P.St^'^^^J- ^' ELLERMAN

WITH A LIST OF NAMED FORMS (1758-1936)

BY R. W. HAYMAN and G. W. C. HOLT

VOLUME II. FAMILY MURIDAE

LONDON:

PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM

Issued 2ISI March, 1941] [Price One Pound Fifteen Shillings

Sold at The British Museum (Natural History), Cromwell Road, S.W;

and by

B. QuARiTCH, Ltd.; Dulau & Co., Ltd.;

and the Oxford University Press

(All rights reserved)

made and printed IX GREAT BRITAIN" BY' JARROLD and SONS LTD. .NORWICH

CONTENTS

Order RODENTIA

Superfamily MUROIDAE Family Muridae Subfamily Murinae

Genus Eliurus, Milne-Edwards Genus Anisomys, Thomas Genus Hapalomys, Blyth Genus Pogonomys, Milne-Edwards Genus Lenomys, Thomas Genus Chiropodomys, Peters Genus Vandeleuria, Gray Genus Micromys, Dehne Genus Apodemus, Kaup Genus Thamnomys, Thomas Genus Grammomys, Thomas Genus Carpomys, Thomas Genus Batomys, Thomas Genus Pithecheir, Cuvier Genus Crateromys, Thomas Genus Hyotnys, Thomas Genus Mallomys, Thomas Genus Coniluriis, Ogilby Genus Zysomys, Thomas Genus Laomys, Thomas Genus Mesembriomys, Palmer Genus Oenomys, Thomas Genus Mylomys, Thomas Genus Dasymys, Peters Genus Arvicanthis, Lesson Genus Hadromys, Thomas Genus Pelomys, Peters Genus Lemniscomys, Trouessart Genus Rhabdomys, Thomas (ienus Hyboniys, Thomas

30 75 77 79 81

83 84 86 89 92

103 104 107 108 109 no III 112

"3 114

115 116 118 119 120 123 127 127 130 133 135

CONTENTS

Genus Millardia, Thomas .

Genus Pyromys, Thomas

Genus Dacnomys, Thomas .

Genus Eropeplus, Miller & HoUister

Genus Stenocephalem\s, Frick

Genus Aethomys, Thomas .

Genus Thallomys, Thomas .

Genus Rattiis, Fischer

Genus Gyomys, Thomas

Genus Leporillus, Thomas .

Genus Pseudomys, Gray

Genus Apoinys, Mearns

Genus Melomys, Thomas

Genus Uromys, Peters

Genus Coelomys, Thomas

Genus Malacomys, Milne-Edwards

Genus Haeromys, Thomas .

Genus Chiromysciis, Thomas

Genus Zelotomys, Osgood

Genus Hylenomys, I'homas .

Genus Muriculus, Thomas .

Genus Mtts, Linnaeus

Genus Mycterom\s, Robinson & Kloss

Genus Leggadina, Thomas .

Genus Colomys, Thomas & Wroughton

Genus Nesoromys, Thomas .

Genus Crunomys, Thomas .

Genus Alacriiromys, Stein

Genus Loplniromys, Peters .

Genus Notomys, Lesson

Genus Mastacomys, Thomas

Genus Golunda, Gray

Genus Echiolhrix, Gray

Genus Acomys, Geoffroy

Genus Uranomys, Dollman .

Genus Bandicota, Gray

Genus Nesokia, Gray .

Genus Beamys, Thomas

CONTENTS

Genus Saccostomus, Peters . Genus Cricetomys, Waterhouse Genus Phloeomys, Waterhouse

Subfamily Rhynchomyinae . Genus Rhynchomys, Thomas

Subfamily Hydromyinae Genus Hydromys, Geoffrey Genus Parahydromys, Poche Genus Crossomys, Thomas Genus Chrotomys, Thomas Genus Celaenomys, Thomas Genus Leptomys, Thomas Genus Xerotnys, Thomas

Subfamily Dendromyinae Genus Dendromiis, Smith Genus Steatomys, Peters Genus Malacothrix, Wagner Genus Prionomvs, Dollman Genus Petromysais, Thomas

Subfamily Deomyinae . Genus Deomvs, Thomas

Subfamily Otomyinae . Genus Otomvs, Cuvier Genus Parotomys, Thomas

Subfamily Cricetinae . Genus Oryzomys, Baird Genus Megalomys, Trouessart Genus Neacomys, Thomas Genus Nectomys, Peters Genus Rhipidomys, Tschudi Genus Thomasomys, Coues Genus Phaenomys, Thomas Genus Chilomys, Thomas Genus Tylomys, Peters Genus Ototylomys, Merriam Genus Nyctomys, Saussure Genus Nesomvs, Peters Genus R/hi»omvs, Thomas .

283 286 291 296 296 297 298 300 301 302 302 303 304 305 306

311 313 315

315 316

317 318 318

325 326

340 359 360 361

363 366

37> 372 373 374 374 375 377

CONTENTS

Genus Reithrodontomys, Giglioli Genus Peromyscus, Gloger . Genus Baiomys, True Genus Calomyscus, Thomas . Genus Onychomys, Baird Genus Akodon, Meyen Genus Zygodontomys, Allen Genus Microxiis, Thomas . Genus Lenoxus, Thomas Genus Oxymycterus, Waterhouse Genus Blarinomys, Thomas Genus Notiomys, Thomas Genus Scapteromys, Waterhouse Genus Scotinomys, Thomas . Genus Cricetulus, Milne-Edwards Genus Phodopus, Miller Genus Crketiis, Leske Genus Mesocricetus, Nehring Genus Mystromys, Wagner . Genus Hesperotnys, Waterhouse Genus Eligmodontia, Cuvier Genus Graomys, Thomas Genus Phyllotis, Waterhouse Genus Chinchilhda, Thomas Genus Irenomys, Thomas Genus Neotomys, Thomas . Genus Reithrodon, Waterhouse Genus Euneomys, Coues Genus Chelemyscus, Thomas Genus Holochilus, Brandt Genus Sigmodon, Say & Ord Genus Sigmomys, Thomas . Genus Andinomys, Thomas . Genus Neototnodo7i, Merriam Genus Neotoma, Say & Ord Genus Hodomys, Merriam . Genus Nelsonia, Merriam Genus Hvpogeomvs, Grandidier

CONTENTS

Genus Ichthyomys, Thomas

Genus Rheomys, Thomas

Genus Anotomys, Thomas . Subfamily Gymnuromyinae .

Genus Gymnuromys, Forsv-th Major Subfamily Tachyoryctinae .

Genus Brachyuromys, Forsyth Major

Genus Tachyoryctes, Riippell Subfamily Gerbillinae

Genus Gerbillus, Desmarest

Genus Microdillus, Thomas

Genus Tatera, Lataste

Genus Taterillus, Thomas .

Genus Desmodillus, Thomas & Schwann

Genus Desmodilliscus, Wettstein .

Genus Pachyuromys, Lataste

Genus Ammodilliis, Thomas

Genus Meriones, Illiger

Genus Psammomys, Cretzchmar .

Genus Brachiones, Thomas .

Genus Rhombomys, Wagner Subfamily Myospalacinae

Genus Myospalax, Laxmann Subfamily AIicrotinae .

Genus Brachytarsomys, Giinther .

Genus Dicrostonyx, Gloger .

Genus Synaptomys, Baird

Genus Myopiis, Miller

Genus Lemmus, Link .

Genus Clethrionomys, Tilesius

Genus Aschizomys, Miller .

Genus Eothenomys, Miller .

Genus Antelioinys, Miller

Genus Alticola, Blanford

Genus Hyperacrius, Miller .

Genus Phenacomys, Merriam

Genus Dolomys, Nehring

Genus Orthriomys, Merriam

483 487

491 492

497 500

510 510 520 522 523 523 524 525 537 538 539 541 541 548 555 556 558 560

561 565

574 575 577 578 581 582 584

58^-

< CONTENTS
	PAGE
Genus Herpetomys, Merriam . ...	586
Genus Microtus, Schrank				586
Genus Lasiopodomys, Lataste						616
Genus Proedromys, Thomas						617
Genus Phaiomys, Blyth						617
Genus Neodoii, Hodgson						618
Genus Pedomys, Baird						620
Genus Pitymys, McMurtrie						621
Genus Blmifordimys, Argyropulo						626
Genus Anicola, Lacepede .						627
Genus Lagurus, Gloger						633
Genus Neofiber, True .						63s
Genus Ondatra, Link .						636
Genus Prometheomys, Satunin						638
Genus Ellobius, Fischer						639
Appendix I. List of new names pubHshed in this work	643
Appendix IL Correction to List of named forms in genus Sciuru
(Vol L p. 343)	'J43
\pPENDix IH. Further notes on named forms ir	the genus	Rattii		''44

LIST OF TEXT-FIGURES

14-

23- 24.

25- 26.

27- 28. 29. 30- 31- 32.

Anisomys imitator, Thomas ....

do.

do. Micromys minutus, Pallas ....

do.

do. Apodemus sylvaticus, Linnaeus ....

do.

do. Rattus rattus, Linnaeus ....

do. R. rattus, Linnaeus and R. norvegiais, Berkenhout Rattus (Micaelamys) granti, Wroughton Rattus rattus, Linnaeus ....

Acomys dimidiatus, Cretzchmar

do. Acomys dimidiatus minous, Bate Cricetomys gambianus, Waterhouse

do.

do. Cricetulus migratorius, Pallas ....

do.

do. Cricetus cricetus, Linnaeus ....

do.

do. Mesocricetus nezctoni, Nehring ....

do.

do. Gymnuromys roberti, Forsyth Major . Tachyoryctes cheesmani, Thomas

do.

do.

	PAGE
Skull X I	78
do.	78
Cheekteeth x 7	79
Skull X 5	88
do.	88
Cheekteeth X 13	89
Skull X3i	94
do.	94
Cheekteeth x 10	95
Skull X2i	152
do.	153
Cheekteeth X 5	153
Cheekteeth x 13	1 70
do. X 10
Skull X2i	270
do.	270
Cheekteeth x 10	271
Skull X I	288
do.	288
Cheekteeth X 7	289
Skull X 34	430
do.	430
Cheekteeth x 20	431
SkuUx2	438
do.	439
Cheekteeth x 5	439
Skull X 2i	442
do.	442
Cheekteeth X 13	443
Cheekteeth x 12	489
Skull xii	494
do.	494
Cheekteeth x 6	495

LIST OF TEXT-FIGURES

34-

36. 37- 38. 39-

40. 4'-

4-- 43- 44- 45- 4''- 47- 4S.

49-

5°-

Meriones libycus crassus, Sundevall

do.

do. Myospalax fontanieri fontanus, Thomas

do.

do. Mvospalax psilunis & M. jontanieri, posterior

views

do. Lemmus lemmus, Linnaeus

Clethrionomys glareobis, Schreber

do.

do. Microtiis agrestis, Linnaeus

do.

do. Arvicola ierresiris, Linnaeus

do.

do.

Skull X 2

do. Cheekteeth 12 Skull <ii

do.

do.

Skull X 1 1 Cheekteeth x 7 Skull X 3 Cheekteeth x 9 Skull x 3

do. Cheekteeth x 14 Skull X2i

do. Cheekteeth x 12 Skull X 2

do. Cheekteeth x 8

526 526

527 542 543

543

544 544

563 566 566 567

589 628 628 629

(With the exception of Figs. 9, i.!, 16, and 25, from Miller's Catalogue of the

Mammals of Western Europe, and Figs. 36-38, and 41 from Hinton's Monograph of

Voles and Lemmings, by the same artist, all the figures have been specially drawn for this volume by Mr. A. J. Engel Terzi.)

Family MURIDAE

i8g6. Thomas: Muridae (included Lophiomys). Subfamilies Hydrom>inae, Rhyn- chomyinae, Phloeomyinae, Gerbillinae, Murinae, Dendromyinae, Otomyinae, Cricetinae, Neotominae, Microtinae, " Siphneinae " ^ Myospalacinae. Spala- cidae. part, Rhizomyinae, part {Tachyoryctes).

1899. Tullberg: Families Spalacidae, part (\Iyospalax and Tachyoryctes) ; Neso- myidae; Cricetidae; Arvicolidae ; Hesperomyidae ; Muridae (with subfamilies Murini, Phloeomyini, Otomyini); Gerbillidae.

1918. Miller & Gidley: Family Cricetidae (with subfamilies Cricetinae, Gerbillinae, Microtinae (and included Lophiomyinae)) ; Family Rhizomyidae, part, subfamily Tachyoryctinae ; Family Spalacidae, part, subfamily Myospalacinae; Family Muridae (with subfamihes Dendromyinae, Murinae, Phloeomyinae, Otomyinae, Hydromyinae).

1924. Winge: Family Muridae, part; subfamilies Rhizomyini {Rhisomys, Tachy- oryctes, and genera from Madagascar) ; Cricetini (with groups Criceti (included Lophiomys), Hesperomyes, and Arvicolae); and Murini, with groups Mures, Gerbilli, and Hydromyes.

1928. Weber: Family Spalacidae (part, Tachyoryctes, Myospalax); Family Neso- myidae; Family Muridae (with subfamilies Cricetinae, Microtinae, Murinae, Gerbillinae, Hydromyinae (and included Lophiomyinae)).

Geographical Distribution. — Throughout the Holarctic, Indo-Malayan, Australasian, African and Neotropical re- gions, from Arctic regions of Eurasia south to the Cape of Good Hope, and Tasmania; east to Fiji and other islands of the Pacific; Madagascar; and in the New World from Arctic regions including Greenland south to Tierra del Fuego, and including the Galapagos Islands.

Number of Genera. — I have examined and retained one hundred and eight)'-six genera, divided among twelve subfamilies. At least six, and perhaps more, valid genera are not represented in the British Museum.

(In the first volume, containing all other Rodents, one hundred and forty- seven genera were retained, and four besides these are not represented in London.)

The Family Muridae belongs according to the present classification to the Superfamily Muroidae, a group containing also four families, Muscardinidae, Lophiomyidae, Rhizomyidae, and Spalacidae, which have been dealt with in the first volume. A key to these families has already been given.

Notes on the essential characters of the family Muridae have also been given in Volume I. For reference purposes, these are repeated here.

Char.\cters.— Zvgomasseteric structure primitively (Deomys), nearly as in

Sicistinae (Dipodidae), except that the infraorbital foramen

is more generalized, less enlarged, and not conspicuously wider below than

above. In all remaining genera the zygomatic plate is broadened and tilted

upwards to a greater or lesser degree; masseter lateralis extends its line of

I — Living Rodents — II i

attachment on to zygomatic plate, and masseter lateralis superficialis has its anterior head distinct, so far as known, from the zygoma. Infraorbital foramen always transmitting muscle; but never extremely enlarged; usually or always less so than in such superfamilies as Anomaluroidae, Ctenodactyloidae, Pede- toidae, and Dipodoidae. Mandible with angular portion not distorted outwards by masseter muscle.

Skull usually with constricted frontals; auditory bullae in the majority not much enlarged, but may become so (Gerbillinae); or may be much reduced, as in PMoeomys, etc. Jugal typically considerably shortened; but long in Tachvorvctes and others.

Dental formula in the majority i. {, c. \\, p. M. m. ;: = iC). In some forms the cheekteeth are reduced to 5 (Rhyuchomys, and some Hydromyine genera). In one genus, Dcsmodilliscus, the cheekteeth formula is f . Molars rooted except in Mvospalax, Rhombomys, and the majority of the Microtinae.

Fibula, so far as known, reduced and fused high on the leg with the tibia. Digits of hindfoot five, with the one exception of Malacothrix, in which they are reduced to four. In a few African genera, the forefoot may have three functional digits, or three digits only.

External form as a rule small and generalized; sometimes much modified for underground life (Mvospalax, EUobiiis, Prometlieomys, Notiomys, etc.); some- times highly specialized for aquatic life : cranially as well as externally in Ichtliyonivs and allies, Hydioiiivs, Crossoiiiys; externally in Ondatra, etc. In some forms, hindfoot extremely specialized for arboreal life; a fully opposable and clawless hallux is developed in Hapalomys, Chiropodomys, Vandeleuria, Chiromyscus. In one case, Notomys, and possibly in some Gerbillinae, appar- ently specialized for bipedal saltatorial life. Spiny covering may be developed [Acomys, some species of Rattiis, etc.), but is never comparable to that of specialized Hystricoid Rodents. Tail typically naked and scaly; uniformly haired in Crateromys, one species of Neotoma, most Gerbillinae, and others.

Infraorbital foramen tj'pically specialized into a wider upper portion for muscle-transmission and a narrower lower one for nerve transmission, its lower border very generally V-shaped, and not straight (compare Rhizomyidae). Cheekteeth laminate, cuspidate, or prismatic, but never agreeing in pattern with that of Muscardinidae (i.e., not basin-shaped with weak transverse ridges and corner cusps, nor flatcrowned with a series of raised narrow transverse ridges extending across crown). External form various, but when subfossorial, eyes retained, and zygomatic plate not specially narrowed and turned down- wards (compare Spalacidae). Temporal fossae never roofed in by bony outgrowths (compare Lophiomyidae). Masseter muscle, so far as known, not rising beside infraorbital foramen on its inner side (compare Rliizomyidae).

In this group I recognize twelve subfamilies. The Lophiomyidae, Spalacidae, and Rhizomyidae are probably offshoots of the present family, and are too highly specialized to be included. The Muscardinidae seem to stand very near the Muridae, but to be more primitive than Muridae; that family I regard as fundamentally the most generalized of living Rodents except Aplodontiidae and perhaps Bathyergidae.

MURIDAE 3

With reftrcnct to the cheekteeth formula of Muridae, I must note that according to some authors, the three cheekteeth represent P.4, M.i, and M.2, and it is suggested that M.3 is suppressed. There seems to be considerable evidence in favour of this view'; but for convenience throughout this work I adopt the customary notation.

THE RATS FROM MADAGASCAR

I'here are six genera that I have examined, containing seven well-marked species in all, from Madagascar. They are excessively difficult to classify. Most authors have referred them to a subfamily Nesomyinae, whose sole character seems to be "Habitat in Madagascar," or dumped them all in the subfamily Cricetinae. It does not seem to me possible to take either course.

The sole character given by Tullberg for the group which is unusual among the Muridae he examined is the fact that the tongue possesses three papillae circumvallatae, but he only examined two genera, .Gymnuromys and Eliitrus. But this character, although in most other Muridae he examined was reduced to one, was present in Cricetomys (three); while two were present in Myospalax and Tachyoryctes. It is not a character which one can use throughout the Order; and is apparently variable in closely allied genera in other groups (for instance, Petaurista, o, Pteromys, 3, in the Pteromys group of Sciuridae). It is probably merely a primitive character which may be met with in any group.

The Rats of Madagascar may be arranged as follows, in key form.

Skull specialized, Microtine in aspect, with zygomatic plate strongly tilted upwards, infraorbital foramen small, and temporal ridges fusing to form a median interorbital ridge. Cheekteeth prismatic, but brachyodont. Br.\chyt.\rsomys

Skull without the specializations just described.

Cheekteeth laminate, a series of transverse plates, these plates equal- sized, pressed closely together, the general effect simple. M.3 slightly larger than M.2, and I\1.2 equal in elements to M.i. Eliurus

Cheekteeth never a series of plain transverse plates.

Cheekteeth flatcrowned, the folds of the molars becoming isolated on crown surface as long thick transverse enamel ridges which extend across crown, and in progressive forms cease to appear as re-entrant folds, being completely isolated. Folds much curved. Brachyuromys

This specialization at highest development, M.3 larger.

Brachyuromys ramirohitra

This specialization usually not reached until old age. M.3 smaller.

Brachyuromys betsileoensis

' For a full discussion see Hinton, .\nn. Mag. Nat. Hist, q, XI, p. 162, 1923.

4 MURIDAE

Cheekteeth without the pattern just described.

Cheekteeth completely flatcrowned, the laminae excessively tightly pressed together and compressed; all traces of cusps obliterated; the pattern a series of extremely narrow line-like folds isolated, or nearly so, on crown surface. M.3 is broader and a little longer than M.2, and M.2 is slightly larger than M.I. Gymxuromys

Cheekteeth without the pattern just described.

Cheekteeth hypsodont, prismatic in appearance, with inner and outer re-entrant folds present, but no signs of cusps, the general effect simple. Hypogeomys

Cheekteeth brachyodont, not prismatic, excessively complex, with clear cusps, these arranged biserially; outer main folds of upper molars with subsidiary ridges present (or elements apparently corresponding to them). Nesomy'S

Of these genera, Hxpogeomys has many noticeable external specializations, but the external form of the others, though the size is usually relatively large, is generalized.

A feature in which these Rats differ from normal Muridae is the very general fact that M.2 is scarcely smaller than M.i, and M.3 is often as large as, or larger than, M.2.

Winge referred them all to his Rhizomyini (also containing Tachyoryctes), on this character (M.2 scarcely smaller than M.i), whereas in his Murini and Cricetini (containing the rest of the family), M.2 is "clearly smallei than M.i."

But unfortunately, though very generally so, this is not always the case, as for instance Am'somvs in Murinae, and some American Cricetine genera, which have the elements of M.2 exactly as in M.i.

The cranial peculiarities of Brtuiivtarsoinvs are very similar to those of the Microtinae, except the much less specialized posterior portion of the palate. The molais also are Microtine in aspect, so that Hinton has suggested that this genus will perhaps have to be transferred from the "Nesomyinae" to the Microtinae. It further differs from Microtinae in the brachyodont molars. But the pattern of the cheekteeth, and the specialized Microtine skull (with fused interorbital crest, and weak squamosal crest), occurring together are very significant, and the genus is here regarded as a primitive Microtine.

Brachyuromys resembles Tachyoryctes closely in dental pattern, as long ago was pointed out by Forsyth Major. It differs markedly in dental characters from any Cricetine seen. B. betsileoensis is less specialized, though probably to be considered as a near ally or forerunner of typical Brachyiiromys. The folds are not quite entirely isolated, and are usually separated by a space in the middle of the tooth. The pattern, particularly of M.2, is not altogether unlike that of Sigmodon, among Neotropical Cricetinae. I am uncertain of the status of this form, which should probably form a distinct genus. There is not the slightest doubt in my mind that Tachyoryctes is a member of the Muridae,

and that typical Brachyuromys on account of its dental pattern probably stands very close to it, altlTOugh the pattern might have been derived independently.

From Cricetinae with a similar pattern, B. betsileoemis differs in the more reduced M.i, just as does Nesomys from the Oryzomys group of Cricetine genera.

XesoHiys is the most primitive genus from Madagascar dentally. The cusps are developed as in, and the general pattern is similar to the very complex-toothed Neotropical Cricetinae like Oryzomys, differing, however, in at least two very- important characters; M.2 is similar in elements to .M.i in Xesomys, more reduced than M.i in elements in Oryzomys; and M.i in Nesomys has the antero- internal corner evenly rounded, and apparently lacking all traces of the anterointernal cusp, which is always conspicuous in Oryzomys and allies.

Hypogeomys is also similar to Cricetine genera, but right at the other end of the series ; being most like Neotoma or that section of Cricetinae in dental characters; a highly specialized hypsodont more or less prismatic dentition, with inner and outer folds (in Hvpogeomys narrow, and not well open), and all traces of cusps obliterated. The pattern is more or less similar in all upper teeth, but AI.3 is a little reduced. It differs from Xeotoma and prismatic Cricetinae in the suppression of the anterointernal fold of M.i, in this character (reduction of anterointernal side of M.i), differing from Xeotoma jxisi as Xesomys differs from Oryzomys. The pattern is not as "Microtine" as in Xeotoma, but is compared with that genus because it seems to be more near it than to any of the others.

Gxmnuromxs is probablv a derivative of Xesomys. But it is extremely highly modified dentallv, differing in general dental effect from all other Muridae, and indeed from all Rodents examined. The general ridge-plan is similar to that of Xesomys, and also as I have noted seems to have some similarity to that of the Dormouse Platacanthomys, though the dental effect of all three genera is very different.

Eliurus is running parallel to the most highlv specialized Murinae (Phloeomys, etc.). The cheekteeth are, apparently from birth, a series of absolutely trans- verse plates. This is the most simplified pattern known among the Rats of Madagascar. The plates are pressed together (though nothing like so tightly as those of Gymntiromys), and further differ from those of Gymmiromys in being straight instead of considerably curved. It differs from Murinae in the character usual to these Madagascar genera, namely, M.2 is not reduced in elements; and here, as in Gymmiromys and others, M.3 tends to be slightly larger than M.2. There is, however, no tendency towards reduplication of elements such as is found in Otomyinae, another group \\ ith the molars a series of transverse plates.

These Rats must have been isolated very early in Madagascar — perhaps before the various subfamilies of Murinae as we now accept them w'ere fully differentiated. Free from competition, they retain many primitive characters such as are not usually met with elsewhere in Muridae ; yet they parallel different groups of Muridae in essential development. The key I have listed above shows that there are no characters which will hold this group together as a subfamily, and that they are strongly differentiated, (.\part from the primitive character of a relatively long jugal, which may be met with any^vhere independently

within the Muridae, their cranial characters are not pecuHar, and certainly will not divide them from other Muridae.)

I have therefore no alternative but to refer them to different subfamilies.

Braclivtarsoinvs is regarded as a primitive Microtine ; Brachyuromys is referred to the Tachvoryctinae ; Gymnuromys must, I think, be retained apart from all other Muridae as type of a special subfamily; Nesomys is a primitive member of the Cricetinae, and Hypogeomys is one of the most highly specialized Cricetinae known; Eliurus I refer to the Murinae, though it is not closely allied to other Murinae. It is curious that Eliurus, which is the most specialized dentally of all Madagascar Rats, according to the theories held here, should be referred to the Murinae, which are regarded as dentally the lowest subfamily in the group. The specialization reached by Eliurus is in essential pattern as high as the most specialized dental type known in Murinae, Phloeomys; but the proportions of the teeth are more primitive than in any knovi'n Murine except perhaps Anisomvs.

Key to the Subf.\milies of Muridae

Zvgomatic plate completely beneath the infraorbital foramen.

Subfamily Deomyin.\e {Deomys) Zvgomatic plate tilted upwards to a greater or lesser degree.

Cheekteeth prismatic in pattern, frequently evergrowing. Skull much specialized, either for underground life, or by ridges for attachment of jaw muscles.

Zygomatic plate not tilted strongly upwards; infraorbital foramen large ; lambdoid crest slanting forwards to posterior zygomatic root. (External form is much specialized for underground life; cheekteeth evergrowing.) Subfamily Mygsp.alacinae

(Myospalax)

Zvgomatic plate tilted very strongly upwards; infraorbital foramen small, narrowed and reduced ; lambdoid crest not slanting for- wards to level of posterior zygomatic root. (The skull is pro- foundly modified by ridges for jaw-muscle attachment, with tendency to develop median interorbital crest, squamosal crests, etc.) Subfamily Microtinae

Cheekteeth brachyodont; third lnwer nidlar not reaching down to

level of incisors. Group Brachytarsomyes

{Brachytarsomys)

Cheekteeth strongly hypsodont ; third lower molar always reaching down to level of incisors.

Lower incisor short, lingual to molars. Group Lemmi

{Dicrostonyx, Syiiap/oiuys. Myopus, Leinmus)

Lower incisor long, passing from lingual to labial side of molars

between bases or roots of M.2 and M.3. Group Microti

{Clethrionomys, Aschizomys, Eothenomys, Anteliomys, Alti- cola, Hyperacrius, Dolomys, Phenacomys, Arvicola, Phaio- mys, Blanfordimys, Pitymys, Neodon, Pedomys, Proedromys, Orthriomys, Herpetomys, Microtus, Lasiopodomys, Lagtirus, Ondatra, Neofiber, Prometheomys, Ellohius)

Cheekteeth various, but with one exception (out of over a hundred and fifty genera), not evergrowing ; when prismatic the skull is not much specialized by ridges for jaw-muscle attachment, as described above, nor for underground life.

Upper incisors vestigial. Cheekteeth so reduced as to be almost

invisible to the naked eye. Subfamily Rhynchomyin.\e

[Rhynchomys)

Upper incisors and cheekteeth never excessively reduced.

Skull specialized, with tendency to great inflation of auditory bullae, enlargement of braincase, and weakening of rostrum, its general tj'pe suggestive of that found elsewhere in bipedal saltatorial Rodentia, such as Dipodidae, or Heteromyidae. Limbs with tendency towards lengthening; external form always specialized for life in plains or desert regions. (In one genus, molars evergrowing; the cheekteeth are primitively with cusps arranged biserially in the upper series, progressively becoming a series of laminae separated by relatively wide inner and outer re- entrant folds, the folds approximately opposite and equal, the general effect simple.) Subfamily Gerbillin.^e

(Taiera, Taterillus, Gerbillus, Microdillus, Desmodilliis, Des- modillisais, Pachyuromys, Ammodillus ; Meriones, Psammomys, Brachiones, Rhombomys)

Skull never specialized as just described, with less tendency to inflation of bullae, etc. (In most forms the skull is relatively generalized.)

Cheekteeth a series of transverse plates; M.3 becoming the dominant tooth, always larger than M.2, usually larger than M.I, and with reduplication of elements.

Subfamily Otomyinae {Otomys, Parotomys)

Cheekteeth when a series of transverse plates never with M.3 the dominant tooth. M.3 without reduplication of elements.

Cheekteeth completely flatcrowned, the laminae excessively tightly packed together and compressed, the pattern a series of extremely narrow line-like folds isolated, or nearly

MURIDAE

so, on crown surface. M.3 is broader and a little longer than M.2, and M.2 is slightly larger than M.i.

Subfamily Gymn'uromyinae (Gymniirotnys) Cheekteeth never with the pattern just described.

Cheekteeth with the re-entrant folds isolating to form

extremely thick parallel curved ridges extending across

flat crowns; the general effect in elements considerably

simplified in fully adult. Subfamily T.'vchyoryctinae

Skull much specialized for fossorial life. Jugal tending

to extend to the lachrymal. Group Tachyoryctae

( Tachyoryctes) Skull generalized. Jugal long, but not extending to

lachr\mal. Group Brachyuromyes

{Brac}ixiiromys) Cheekteeth witli re-entrant folds not isolating to form thick parallel ridges; when isolating, the elements not reduced, and the general pattern more complex, and the isolation of the folds less complete. Cheekteeth cuspidate, laminate or prismatic; when cuspi- date, the cusps of the upper molars arranged in two longitudinal rows ; and the laminae bearing the cusps separated by wide folds. (When prismatic, skull not specially modified, compare Microtinae.)

Subfamily Cricetinae

{Orvso)n\s, Meg<ilu))ivs, Xcacomvs, Nectomvs, Rhipi-

domvs, Tlwvuisomxs, Phaenomvs. Chilom\s, Tvloiiivs.

Ototyloniys, .Xyctoiiiys, Otonvctomys (the last not

seen), Nesomys, Rhagomys, Reithrodoiitomvs, Pero-

mysciis, Baiomys, Caloiiiyscus, Onvcliomys, Akodon,

Zygodontomys, Microxiis, Lenoxus, Oxvi'ivcterus,

Blarinomvs, Not win vs, Scapteromys, Scotlnomys,

Cricetidiis, Cricetus, Phodopiis, Mcsocricetus, Mys-

troinxs. HespcruiiiYs, EUgmodoiitia, Graomvs, PbxUo-

tis, C/iinc/nllida, Irenomvs, Reithrodon, Nfotoiiivs,

Ewieomvs, Chelemyscus, Sigmomys, Sigiiiodoti,

Holoc/iiliis, Andinom\s, Neotoniodon, Teanopiis (the

last not seen), Neotoma, Hodoinvs, Xenoinxs (the

last not seen); Nehonia, Hvpogeoinys, Rheomys,

Ichthyomys, Anotomxs)

Cheekteeth cuspidate or laminate; when cuspidate the

cusps of the upper molars are arranged in three

longitudinal rows; the laminae bearing the cusps are

pressed together, not separated by wide folds.

Cheekteeth simpHfied, more or less basinshaped (prob- ably derived from triserial pattern with the outer row of the upper molars suppressed); M.:t absent or vestigial. Subfamily Hydromyinae

{Xeroinys, Leptomys, Chrotomys, Celaenomys, Pseudohydromys (the last not seen) ; Parahydromys, Hydromys, Crossomys)

Cheekteeth less simplified, and not obviously basin- shaped. M.| present. Inner row of cusps of the upper molars much reduced, so that there is only one functional inner cusp in first and second upper molars. M.§ strongly reduced. Subfamily Dendromyin.^e

{Steatomys, Dendromus, Malacothrix ; Prion- omys ; Peiromyscus)

inner row of cusps of the upper molars not specially reduced, so that there is more than one functional cusp in the first and second upper molars.

Subfamily Murin.ve

M.2 similar in size and elements to M.i.

Lower incisors normal; -\L3 rather larger than

M.2 Group Eliuri

(Eliurus) Lower incisors extremely compressed, and highly specialized; M.3 smaller than M.2.

Group Anisomyes ■ (Anisomys)

M.2 is more reduced in elements than M.i.

Group Mures (Hapalomvs, Pogonumys, Chiropodomys, Vande- leuria, Lenomys, Micromys, Apodemus, Tham- nomys, Grammomys, Carpomys, Batomys, Crater- omys, Pitheclieir, Mallomys, Hyomys, Conilurus, Zyzonns. Laonivs, Mesembriomys ; Oenomys, Mylomys, Dasymys, Anicanthis, Pelomys, Rhab- domys, Lemniscomys, Hybomys, Hadromys, Mil- lardia, Pyromys, Stenoceplialemys, Dacnomys, Eropepliis, Thallomys, Aethomys, Rattiis, Loreiit- zimys (the last not seen), Gyomys, Leporilliis, Pseudo?nys, Apomys, Melomys, I'roniys, Coelomys, Malacomys, Haeromys, Chiromyscus, Zelotomys, Colomys, Xesoromys, Leggadina, Mus, Miiriculus, Hylenomys, Mycteromys, Crunomys, Macrtiromys;

Notomys; Mastacomys ; Golunda; Lophiiromys , Uranomys, Acomys; Echiothrix, Melasmothrix (the last not seen); Beamys, Saccostomus; Cricetotnys; Bandicota, Nesokia; Phloeomys)

DISTRIBUTION

Below is given a list of the genera, principal species, and their approximate ranges, of the family .Muridae, in the geographical regions of the world. A similar list, including the Rodentia other than Muridae, will be found in Vol. I.

Ml'RlDAE OF THE PaL.'VEARCTIC

Genus Micronixs

iiiiiiutus. England, Central Europe, north to Germany, south to Frailce, Italy, Rumania; Finland, Russia; Siberia to Amur region; Szechuan; Japan. Genus Apodeimis

iiiYstaciiiiis group. Asia Minor, Greece.

svh''Jticiis group. All Europe (including Iceland). Siberia, to Altai; Turkestan. Asia Minor, Syria, Persia, Kashmir; Morocco. geisha group. Japan.

speciosiis group. Eastern Siberia; Japan; Szechuan, Manchuria. agrarius group. Eastern Europe (Germany to Bulgaria); Russia, Turkestan; Ussuri (East Siberia). Szechuan, Kansu, Man- churia, Shantung, Korea. Genus Arvicaiithis

luloticus. Egypt. Genus Lemniscomys

barharus. Morocco. Genus Millardia

fiieltadn. Punjab, (jenus Rtittiis

icilliis group. Throughout Europe. Russian Turkestan. Tibet,

Kashmir; Japan; Egypt, Syria, etc. Morocco. norvegkiis group. Throughout Europe. Siberia; Manchuria,

Shansi, Kansu, and most of Palaearctic China. confucianus group. Szechuan, Tibet, Shantimg, Shensi, Chihli. edwardsi group. Szechuan. concha group. Morocco. Genus Mus

inuscidus group. Throughout the entire Palaearctic region. boodiiga. Punjab. p/dlvihn'x. Punjab. Genus Goliiiidii

clliiiti. Punjab and Nortii-west Frontier.

MURIDAE II

Genus Acomys

russatus. Egypt, Sinai.

cahirinus group. Egypt, Tripoli, Cyprus, Crete. Genus Bandicota

bcngalensis. Kashmir. Genus Nesokia

indica. North-west Frontier, Afghanistan, Russian Turkestan, Chinese Turkestan; Mesopotamia, Syria, Palestine, Egypt. Genus Calomysciis

baihvardi. Persia, Baluchistan, Russian Turkestan. Genus Cricetidus

harabensis group. South Siberia, west to Barnaul, east to Amur;

Mongolia, Manchuria, Chihli, and Shantung. longicaudatus group. Tibet, Shansi, Chihli, Mongolia, Kansu, and

Minussinsk district (Siberia). lama group. Tibet, Kashmir. migratorius group. Greece, South Russia, Syria, Asia Minor,

Persia, Russian and Chinese Turkestan. eversmanni group. South-east Russia, Turkestan, Mongolia. triton group. Kansu, Shantung, Shensi, Chihli, Korea, and South Ussuri. Genus Phudopus

soiigorus group. Southern Siberia (East Kazakstan to Trans- baikalia), and Mongolia. roboroz'skii group. Shensi, Tibet, Mongolia, (?) Manchuria. Genus Cricelus

cricetus. Belgium, North France, Germany, Hungary, Yugoslavia, Rumania, Russia, Caucasus, Turkestan to Minussinsk; (?) Iraq. Genus Mesocricetus

auratiis group. Caucasus, North Persia, Syria, Rumania, Bulgaria. Genus Myospalax

fontanieri group. Kansu, Shansi, Szechuan. smithi. Kansu.

psilurus. Chihli, Manchuria, Transbaikalia, Ussuri. myospalax. Russian Altai. armandi group. Mongolia, Irkutsk. Genus Gerbillus

campestris group. Morocco, North Algeria, Tripoli. garamatitis group. Algeria; Baluchistan. dasyurus group. Egypt, Sinai, Palestine. «>no«/ group. Algeria; Egypt.

gerbillus group. Algeria across North Africa to Syria and Meso- potamia. pyramidum group. Morocco across North .\frica to Eg\-pt, Palestine.

12 MURIDAE

Genus Talira

iiiilicci. Punjah, Persia, Mesopotamia, Syria. Genus Paclniiroinvs

tii(/>ias!. \orth Algeria; ligvpt. Genus Mcriones

calimis. Sinai.

persiciis group. Persia, Baluchistan, Russian Turkestan, Trans- caucasia. titmaricinus group. Palestine, Syria, Asia .Minor, Caucasus, South- east Russia, Russian Turkestan, Gobi desert, Chinese Turkestan. //7»vo/.j group. Egypt, Tripoli, .Algeria; Morocco; Palestine, Svria, Afghanistan, Persia, Russian Tiu'kestan, Transcaucasia, Gobi desert. incrldianus group. South-east Russia, Caucasus, Russian Turkes- tan, Mongolia, Shansi, Chihli. iiiii^uiculatiis. Mongolia, Shansi, Transbaikalia. hiiniiiihie. Punjab, Xorth-west P'rontier. Genus Psaiiniiuiins

obcsiis group. ,\lgcria, Tripoli, ligvpt. Palestine, (jenus Brtichioncs

przcu-dhkii. Chinese Turkestan, Gobi desert. Genus Rhotiibomvs

opiums. Russian Turkestan, Chinese Turkestan, Mongolia. Genus Diciostuny.x

torqiiatus. Arctic Russia, Siberia, and islands to the north. Genus Myopus

schisticolor. Scandinavia, North Russia, .-\ltai, Xorth-east Siberia, North Alongolia. Genus Lenuims

lemmus. Scandinavia, North-west Russia.

ubcmis group. Northern Russia, Siberia, and islands to the north. Genus Cletlirioiiomvs

glareoliis group. Europe from S\\ eden to Pyrenees and Yugoslavia, and England eastwards to Ural Alountains. Tianshan; Syansk Mountains (west of Eake Baikal). iiageri group. Switzerland, Italy, A'ugoslavia, France; Norway;

Hebrides; Channel Islands; Asia Alinor; Tianshan. rutihis group. North Scandinavia, Northern Russia and Siberia;

Japan. To Altai, Manchuria. rujocanus group. Scandinavia, Russia, Siberia to Kamtchatka; Korea, Kansu, Shansi, Szechuan, Hupeh; Mongolia, Chihli; Japan. {sikotanensis {CIct/iiioiioiiivs .'); Kuriles.)

Genus Aschizomys

lemmimis. Xorth-east Siberia.

Genus Eothenoinys

inekmogaster . Szechuan.

Genus Anteliomys

chinensis group. Szechuan.

Genus Alticula

roylei group. Russian Turicestan, Chinese Turkestan, Kashmir,

Tianshan, MongoUa. stoliczkanus group. Tibet, Kashmir. macrotis. Syansk Mountains (Siberia). strelzowi group. Siberian -\ltai, Mongolia.

Genus Hyperacrius

uvnnei group. Kashmir, Punjab. Genus Dolomys

bogdanuvi. Yugoslavia, Greece. Genus Microtia

wrestis group. Europe, including Scandinavia, England and

Hebrides, Spain (and south to North Italy, Yugoslavia);

U.S.S.R. to Lake Baikal; Mongolia; Zungaria. analis group. Europe, south of Baltic ; Orkneys, Channel Islands

(not England); (south to Spain and Greece); Asia Minor,

Russia, Caucasus, Turkestan, Altai, Transbaikalia, Mongolia,

Kansu, Korea, Japan. oeconomus group. Scandinavia, Holland, Germany, Hungary-,

Russia," Siberia to Pacific coast, and Semirechyia. guentheri group. Greece, Asia Minor, Palestine, Libya; Spain. nivalis group. Spain, France, Switzerland, North Italy, South

Germany, Yugoslavia ; Caucasus, Asia Minor, Syria, Palestine. socialis group. Persia, South Russia, Russian Turkestan. roberti group. Asia Minor, Caucasus. calamorum group. Transbaikalia, Ussuri, Manchuria, Shensi,

Kiangsu. middendorffi group. Siberia (Ural, Ob, Yenesei regions). oregalis group. Throughout Northern Siberia, south to Northern

Kazakstan; Mongolia, Chinese Turkestan. millicens. Szechuan. mandarinus group. Shansi, Mongolia, Chihh.

Genus Lasiopodomys

braiuiti. Mongolia, Manchuria, Transbaikalia.

Genus Proedromvs

bedfordi. Kansu. Genus Phaiomys

leiiairiis group. Tibet, Chinese Turkestan, North India (Upper Sutlej valley).

14 MURIDAE

Genus Neodon

carriithersi. Russian Turkestan.

juldaschi. Russian Pamir.

otiiscus, etc. Kansu, Szechuan. Genus Pitymys

siibterraneiis group. Belgium, France. Hungary, Rumania, Switzer- land, Italy, Yugoslavia, Ukraine, Asia Minor, Caucasus.

saiii group. Sicily, Italy, South France.

iben'ciis group. Spain, South France; Greece, Montenegro. Genus Blanfordiiiiys

afghdnus group. Afghanistan, Russian Pamir. Genus An-icola

terrestris group. Europe (except Ireland); Siberia, to Amur River; Turkestan; Syria, Persia. Genus Lagurus

lagurus group. South Russia, Turkestan to Zungaria.

luieus group. Russian Turkestan, Chinese Turkestan, Zungaria, Zaidam, Mongolia. Genus Proinet/ieomys

schaposchnikoici. Caucasus. Genus EUobius

talpiniis group. South Russia, Turkestan, x\ltai, Ciiinese Turkes- tan, Mongolia.

fuscocapilliis group. Baluchistan, Afghanistan, South Russian Turkestan, Persia, Asia Minor.

MURIDAE OF THE NeARCTIC

Genera, principal species, and approximate ranges. (Canada and U.S..\. The House-Rats, and House-Mice, Raftiis rattiis, R. norvegicus, and Miis musailus, are introduced; these species may occur in any part of the world.)

Genus Oryzomys

palustris group. Florida, Texas, and South-eastern United States. Genus Reithrodoutomys

hiamdis group. South Carolina, Virginia, Texas, Nebraska.

megalotis group. Colorado, Kansas, New Mexico, Arizona, California, Idaho.

fulvcscens group. Texas, Oklahoma, Louisiana. Genus Peruiiivsciis

califoinicus group. Idaho, Utah, California, New Mexico, Arizona.

maniculatiis group. Throughout the area: Labrador to Alaska; California to Florida.

leiicopus group. Texas, Arizona, north to Massachusetts, New York, and Montana; Florida, Georgia, Alabama.

boylii group. California, LItah, Texas.

truei group. New Mexico, Colorado, California.

MURIUAE IS

{Peromyscus) nutlalli group. Virginia, South Carolina, to Arkansas.

jloridanus group. Florida. Genus Baiomys

taylori. Texas. Genus Onychomys

leucogaster group. North Dakota, Idaho, New Mexico, Oregon, Utah, Arizona, California, Te.xas, Oklahoma, north to Alberta, Saskatchewan. CJenus Sigmodon

hispidus group. Florida, Te.xas, Arizona. fulviventer group. Texas, New Mexico. Genus Neotoma

floridana group. Florida, Louisiana, Illinois, Nebraska, Kansas,

Texas, New Mexico. albigula group. Arizona, California, New Mexico, Utah, Colorado. intermedia group. California, Arizona. mexicana group. Colorado, Arizona, New ^Mexico. desertortim group. California, Utah, Arizona. pennsyhanica group. Pennsylvania, to Tennessee. fuscipes group. California.

cinerea group. California, Nevada, Alberta, British Columbia, Washington, Oregon, Arizona, Colorado, South Dakota. Genus Dicrostonyx

luuhonius. Labrador.

rubricatus, etc. Alaska, Arctic Canada; Greenland. Genus Synaptomys

cooperi. New Jersey, Virginia, Quebec, west to Kansas and

Minnesota. borealis. Alaska, Mackenzie, British Columbia, Washington ; Labrador; New Hampshire. Genus Lemmus

trimucronatus, etc. Alaska, Mackenzie, Alberta, to Baffin Land. Genus Clethrionomys

daicsoni, and allies. British Columbia, Alaska, Yukon, Ungava,

Oregon. gapperi, and allies. Ontario, New Hampshire, New Jersey, the Dakotas, Mackenzie, Colorado, British Columbia, Idaho. North Carolina. New Mexico. calif ornicus. California. proteus. Labrador. Genus Plienacomys

intermedins group. British Columbia, Washington, Idaho, Cali- fornia, Wyoming, Montana. New Mexico. ungava group. Ungava, Quebec, Labrador, Mackenzie. alhipes group. California. longicaudiis group. Oregon.

Genus Microtiis

peiiiisxhanicus group. Labrador and North Carolina to Alberta,

Alontana, Colorado, New Mexico. Admiralty Island (Alaska).

montanus group. Arizona, Wyoming, California, Utah, Nevada,

Washington, Oregon, British Columbia. californicus group. California. operarius group. Alaska, Mackenzie. abbreviatus group. Alaska.

tozaisendi group. Oregon, California, British Columbia. longicaudus group. Washington to South Dakota, California,

Arizona. Islands off Alaska. mexicanus group. Texas, Arizona.

xanthognathus group. Alberta to Alaska, and Arctic coast. chrotorrhimis group. New Hampshire, Labrador, Quebec, North

Carolina. richardsoni group. Washington, Idaho, Oregon, Wyoming, British

Columbia, Alberta. orcgoiii grou-p. Oregon, California, British Columbia, Washington. Genus Pedomvs

ochrooaster group. Wisconsin, Missouri, Oklahoma, Louisiana, Nebraska, Kansas, the Dakotas, Colorado, Montana, Alberta. Genus Pilviiivs

pinctonim group. Georgia, New York, Mississippi, Oklahoma, Florida. Genus Lagnrus

cnrtotus group. Nevada, Oregon, North Dakota, Washington, Utah, Alberta, Idaho, East Cahfornia. Genus Neofiber

alleni. Florida. Genus Ondatra

zibiihica group. Alaska to Hudson Bay; Labrador; most of U.S.A. except extreme south central portion; and not Florida.

MURIDAE OF THE Inii()-M.\L.\Y.^X ReGION Genus llapaloinxs

hju'^icaudatus group. Tenasserim, Annam, Hainan. Genus Lciioinvs

iiiaviii group. Celebes. Genus CJiiropoddiays

gliroidcs group. Assam, Sumatra (Nias Island), Java, Borneo,

Philippines (Calamianes Island). fuhus. \'unnan. Genus I'liiidchiiria

ohracva group. Peninsular India, Ceylon,