Stoamp-Ruts of East Africa. 169 



June 28th, 1911, and presented by him to the National 

 Collection. 



There is no difficulty in distinguishing this new form from 

 the Elgon species ; the very much larger size, lighter colour, 

 and more arched skull are characters that at once serve to 

 distinguish percivali from jacksoni. Tiie lamina formula is 

 sufficient to separate it from dartmouthi, typus, and fortior, 

 while the double grooving of the lower incisors indicates 

 plainly that it cannot be considered a member of the thomasi 

 group^ with which it has a number of features in common. 



Group 3. 

 m^ with 8 laminse. 



(21) Otomys typus, Heug. 



Oreomys typus, Heuglin, Reis. N. Ost-Afr. ii. p. 76 (1877). 

 Otomys deyeni, Thos. P. Z. S. 1902, ii. p. 311. 



About equal in size to dartmouthi and percivali -, the pre- 

 sence of 8 laminae in m^ easily distinguishes this Abyssinian 

 species from dartmouthi, jacksoni, and percivali. 



In general colour very like 0. t. squalus, dorsal surface 

 brownish buff; head and flanks strongly tinged with buff, 

 yellow rings around eyes very conspicuous. Backs of hands 

 and feet dirty cream-bufF. 



Skull arched, but not so markedly as in the last species. 

 Molars large, m^ with 8 laminae. 



Dimensions (from a spirit-specimen) : — 



Head and botly 161 mm.; tail 90; hind foot 28'5; 

 ear 22. 



Skull (type of degeni) : length from back of interparietal 

 to tip of nasals 36"2 ; greatest breadth 19'7 ; nasals, greatest 

 length 16*5; greatest breadth across anterior expansion 7'5 ; 

 palatilar length 17*7 ; length of palatal foramina 7*4 ; length 

 of upper molar series from front alveolar border to back of 

 m' 10-3, crowns 8-2. 



Hah. Shoa, Abyssinia. 



Thomas has already pointed out * that his degeni is 

 identical with typus of Heuglin, the original description 

 given by Heuglin being "grossly inaccurate." Wroughton 

 in his paper followed this view, and it seems best to adopt it 

 here. The above description is taken from the type-specimen 

 of degeni, which we must now accept as representing typus, 



* Ann. & Mag. Nat. Hist. (7) vol. xviii. p. 302 (1906), 



