DORMICE. RATS, MICE. 633 



Tribe 2. Myomorpha. 



Skull with slender zygomatic arch, clavicles well-developed, except in 

 Lophiomys, tibia and fibula united, infraorbital foramen variable. 



Fam. 5. Gliridae (Myoxidae). Dormice, small, arboreal, with long 

 hairy tails, intestine without caecum, p }, molars rooted, lophodont. 

 Palaearctic, Ethiopian, Oriental. Glis Briss. (Myoxus), Palaearctic, 1 sp. 

 Muscardinus Kaup., Palaearct., 1 sp. M. avellanarius, common dormouse, 

 Brit, and Eur. Eliomys Wagn., Palaearct., 2 sp. Graphiurus F. Cuv. 

 Ethiopian, 13 sp. Platacanthomys Big., Oriental, 1 sp. Typhlomys M. 

 Edw., Oriental, 1 sp. 



Fam. 6. Muridae. Rats, mice, Australian water rat, hamster, etc. 

 Without premolars ; molars rooted or rootless, bunodont or lophodont ; 

 f rentals contracted ; pollex reduced, often with a small nail ; tail rarely 

 densely-haired, sometimes scaly. There are about 86 genera and 724 

 species. Cosmopolitan, being found in Australasia (Hydromys, Xeromys, 

 -Mug, Pogonomys, Craurothrix, Mastacomys, Uromys, Conilurus), and in 

 Madagascar (Brachytarsomys, Nesomys, Hallomys, Brachyuromys, Hypo- 

 geomys, Gymnuromys, Eliurus). The following may be mentioned ; 

 Hydromys Geoff., Australian water-rats, molars , Australia, Tasmania, 

 N. Guinea, 4 sp. Xeromys Thos., m f Queensland, 1 sp. Celaenomys Thos., 

 Chrotomys Thos., Crunomys, RTiynchomys Thos., Phlaeomys Wat., all 

 Oriental with 1 sp. Gerbillus Desm., Ethiop. 20 sp.. Orient. 2 sp., Palaearct. 

 16 sp., burrowers, with tufted tails, jerboa-like. Mus L., rats 

 and mice, largest genus of mammals, Aust. 30 sp., Eth. 30 sp., Orient. 

 50 sp., Palaearct. 20 sp., absent from the New World, 5 British species. 

 M. minutus, harvest mouse, 2^ in. ; M. sylvaticus, wood-mouse ; longer 

 ears than M. musculus, the common house mouse, probably a native 

 of Asia ; M. rattus, the black rat ; M. decunutnus, the Hanoverian rat 

 or brown or Norway rat. Lophiomys M.-Edw., Eth., 1 sp., hallux, 

 opposable, temporal fossa covered by a bony plate from the parietal to 

 the jugal, as in turtles. Cricetus G. Cuv. (Hamster), hamsters, Palae- 

 arct., 12 sp., with large cheek pouches, 8-9 inches, with short tails. 

 Microtus Schrank (Arvicola), voles, Xearct. 40 sp., Palaearct. 40 sp., 

 short ears, short hairy tail, molars composed of triangular prisms placed 

 alternately, 3 British species, M . amphibiua, water-rat, feet not webbed ; 

 M. agrestis, field-vole, occasionally appearing in immense mimbers and 

 doing much damage ; M. glarevhts, bank-vole. Lemmus Link. (Myodes 

 Pall.), lemming, Nearct. 1 sp., Palaearct. 3 sp. ; L. lemmus, the Scandi- 

 navian lemming, 5 inches, at indefinite intervals it multiplies exces- 

 sively, and migrates in a straight line in enormous herds, crossing all 

 obstacles till it reaches the sea into which it plunges in the continuance 

 of its wandering and is drowned ; during the migration, which may last 

 1-3 years, it continues to multiply abnormally and is attacked by all 

 animals en route and destroyed in large numbers ; many perish from 

 disease, due to over-crowding, none appear to return ; the instinct 

 is a good instance of a useless character. Siphneus Bts.. Palaearct., 5 sp., 

 mole-like, subterranean creatures. Fiber G. Cuv., musk-rat, musquash, 

 Nearct., 3 sp., F. osoyoozennis, builds nests on bulrushes above water, 

 carnivorous. Pachyuromys, Ethiop. 1 sp., Palaearct. 1 sp. Meriones, 

 Ethiop. 2 sp., Orient. 1 sp., Palaearct. 10 sp. Psammomys, Palaearct., 2 

 sp. Rhombomy*, Palaearct., 1 sp. Otomys, Eth., 4 sp. Oreinomys, 



