312 MR. OLDFIELD THOMAS ON [NoV. 4, 



1 have much pleasure in naming this distinct species after 

 Mr. Degen, the collector of the present interesting series. 



15. Mus ALBiPES Riipp. 



2 d" , 1 5 . Acldis Ababa. March, April. 



This species is readily distinguished by its long tail from the 

 other members of the group. Mr. Pease also obtained two 

 specimens of it at Lake Zuai. 



16. Mus spp. 



3 c? , 3 $ . Addis Ababa. February to March. 

 2 S ■ Ha wash R. March. 



S . Gubre, Godjam, 6000 feet. 9 May. 



cf . Abulie, Kutai. June. 



Besides the long-tailed, long-skulled M. alhipes, there appear to 

 be more than one species of the difficult macrolepis-lateralis group 

 in the collection, but without further material, with flesh- 

 measurements, it is impossible to distinguish them or make out 

 what names they should bear. Several of Heuglin's names appear 

 to belong to this group. 



17. Leggada MAHOMET Rhoads. 

 S . Addis Ababa. 5 April. 



18. AUVICANTHIS ABYSSINICUS RUpp. 



J 2 . Addis Ababa. March. 

 S 2 . Yah- Yah, Shoa. April. 



4 S • Lake Tsana. May and June. 



(5' 5 . Hawash R. February and March, 



2 . Lake Zuai. March. 



For all these Abyssinian Arvicanthes I provisionally use 

 Ruppell's name of ahyssinicus, with typical specimens of which 

 some of them entirely agree. But on the one hand there may be 

 more than one definable form among them, and on the other 

 identification has to be made of quite a number of other names 

 which have been given to members of the group. Thus Meriones 

 lacernatus RUpp. and Mus ochropus and M. riofidorsalis Heugl, 

 are all evidently forms of Arvicanthis, and will have to be iden- 

 tified when further material is available. But the ISTorth Somali 

 ArvicantJiis, which has been identified with the East-African 

 A. neimianni Matsch., is clearly distinct and is now described \ 



1 Aevicanthis somalictjs, sp. n. 



A small pale species allied to A. neumanni. 



Size markedly less than in the other members of the group. General colour pale 

 sandy buff lined with brown, becoming more " pinkish buff" on the rump. No trace 

 of a spinal dark line. Head paler, almost whitish, ej'e-rings and ears sandy fulvous. 

 Under surface dull whitish, the hairs dark basally. Upper surface of hands and feet 

 buffv white. Tail blackish above, dull fulvous on the sides and below. 



Skull small, strongly built, with strongly-ridged supraorbital region. 



