Mammals from British East Africa. 225 



one. AP with a large antero-internal and a niinnte antero- 

 external secontlary cusp ; inner cusp of main lamina (and 

 also the corrospoiuliiii^ cusp ot" ?/«') large, projected backwai'ls 

 to tiie level of the, pDsteiior lamina, which has no postero- 

 internal cusp. ;)/' with its antero-extcrnal cusp almost 

 obsolete ; its main cus|) longer antero-postcriorly than broad, 

 sharply separated from its large inner cusp, with which it 

 does not fuse. 



Lower molars with their deeply concave grinding-surfacea 

 facing forwards, their beak-like iiinler edges highly raised, 

 il/j with its two anterior cusps unusually small in ])roportiou 

 to the others, perhaps in cross section one third the area of 

 the cusps next succeeding them. No external cingular cusps 

 present. 



'i ype Mylomys Ganinghamei. 



The highly modified teeth of this rat compel me to dis- 

 tinguish it from Pelomys, which it resembles in its general 

 appearance and in the grooving of its upper incisors. The 

 n)olarsof Pelomys an^. much more roundetl in all respects, with 

 low central cusps and without angular projections connecting 

 the laminffi. Jn some respects the molars of the Abyssinian 

 rats which in 1902 ^ 1 assigned with doubt to Pelomys — 

 " P." demheensis and Ilarringtoni — are intermediate between 

 those of Mylomys and Pelomys ; but I am now convinced 

 that these animals should not be included in Pelomys, and 

 think they may be provisionally looked upon as aberrant 

 members of (Enomys, the so-called grooving of their upper 

 incisors being hardly worthy of the name, and their molars 

 being very similarly formed to those of that group. 



In any case the striking rat discovered by Mrs. Holms- 

 Tarn cannot be assigneil to any known genus, and needs a 

 special one to be formed for its reception. 



Mylomys Cum'nghamei, sp. n. 



General appearance very much as in Pelomys falla.v. Fur 

 coarse and harsh ; hairs of back about 15 mm. in length. 

 Colour above coarsely grizzled brown or dull bufFy, becoming 

 rather more rufous on the rump. Under surface dull whitish, 

 the bases of the hairs slaty. Ears broad, rounded, uniformly 

 brown. Arms grizzled brown and buffy ; hands dark bufty. 

 Legs and feet reddish buffy, the skin of the feet brownish. 

 Tail well haired throughout, the hairs almost hiding the scales, 

 which are large, about ten to the centimetre; in colour it is 

 markedly bicolor, blackish brown above, dull bufFy below. 



* P. Z. S. 1902, ii. p. 313. 



