MAMMALIA. 673 



tubercles, little distinct ; anterior molar larger. Feet pentadacty- 

 lous, posterior semi-palmate. Tail thick at the base, thinlj haired, 



romid. Dental formula Owen, c. ^ , p. = , m. j = 12. 



Sp. Hydromys cJirysogaster Geoffr., Guee. Iconogr., Mammif. PL ^s, fig. 

 I ; — Hydromys leucogaster Geoffr. On this genus from New Holland 

 and Van Diemen's Land, compare Geoffrot Saint-Hil., Ann. du Mus. 

 VI. pp. 88—90, PI. 36. 



Mus L. (excl. of several species). Incisors almost always 



3 — 3 



smooth in front. Molars 1^ — ^ , enamelled uniformly, obtusely 



o — o 



tuberculate, the premolar the largest of all. Ears rounded, some- 

 what naked, exsert. Fore feet tetradactylous, with hallucar wart 



unguiculate, hind feet pentadactylous. Dental formula, i. "~ 

 1-1 2-2 _ 



p- r=T'^- 232 = 1^- 



1-1' 



A. Tail thinly haired, ringed ivith scales in whorls, mostly long. 

 + WitJi internal buccal pouches. 



Cricetomys Waterhouse. Head pi-otracted. Tail long. 



Sp. Mus goliath Eueppell, Cricetomys gambianus Waterhouse, Proceed, of 

 the Zool. Sac. 1840, pp. i, 2. Edepp. Mus. Senclcenb. in. s. 114, Tab. 9, 

 Tab. 10, fig. I (cranium). A very large rat from West Africa ; greyish-red ; 

 belly, toes, and tip of tail white. 



Saccostomus Petebs. Tail somewhat short, obscurely annulate, 

 thinly haired. 



Sp. Saccostomus lapidarius Peters, lieise nach Mossamhique, Zool. i. Taf. 34, 

 fig. 3, &c. 



++ With buccal pouclies none. 



Mus (in stricter sense). Incisors smooth in front. 



Sp. Mus Rattus L., Buff. vii. PI. 36, Schreb. Sdugth. Tab. 179; the rat, 

 house-rat, black rat; black-grey on the back; fur glossy; tail of the length 

 of the body. The ancients were not acquainted with this animal ; accord- 

 ing to some this species was imported from America ; others suppose it to 

 have come from the East. — 3fus decumanus Pall., Buff. viii. PI. 27, 

 Schreb. Sdugth. Tab. 1 78 ; the broivn rat, le surmulot (Buff.), die Wander- 

 rafte; brownish-grey; tail shorter than the body. This species, which first 

 penetrated into Western Europe from the East in the middle of the last 

 century (compare Buffon, viii. p. 206), is now in many countries more 

 common than the preceding, which has been expelled by it ; it surpasses 



VOL. II. 43 



