new West African Mammals. 353 



Tatera guinea?, sp. n. 



Allied to T. kempt, Wr., but smaller. 



External proportions and colour quite as in T. kempi, 

 except that li^ht patches are present behind the eyes and the 

 tail is rather more tufted, the hairs of the tuft 7-8 mm. in 

 length. 



Skull in its general shape quite like that of T. kempi, but 

 smaller throughout. Posterior palatine foramina lengthened. 

 Bullae markedly smaller than in kempi, larger than in gracilis. 



Dimensions of the type (measured in the flesh) : — 



Head and body 160 mm. ; tail 172 ; hind foot 3(3 ; ear 21. 



Skull : greatest length 38'(3 ; basilar length 29 ; nasals 15*5 ; 

 interorbital breadth 6'4 ; palatilar length 17"6 ; greatest 

 horizontal diameter of bulla 10 ; upper molar series 6*5. 



Hub. Gunnal, Portuguese Guinea. Alt. 50 m. 

 Type. Adult male. Original number 37. Collected 19th 

 July, 1909, by Dr. W. J. Ansorge. Four specimens. 



This species is as readily distinguishable from T. kempi by 

 its smaller size and smaller bullae as from T. gracilis by its 

 larger size and larger bullae. The greatest horizontal diameter 

 of the bullae in the types of the three species is 8*7, 10, and 

 11 mm. respectively. 



Arvicanthis ansorgei, sp. n. 



A. rvfinus group. 



General characters of A. rufinus and occidentalis *, size 

 intermediate between the two. Character of fur and colour 

 as in A. rvfinus, the area round the base of the tail strongly 

 suffused with tawny. 



Skull slender, its outlines more like those in the larger 

 rvfinus than in the smaller broader-skulled occidenlaUs ; 

 nasals long and slender, evenly tapering backwards ; inter- 

 orbital region narrow ; distance between parietal ridges less 

 than in the smaller occidentalis ; interparietal very small, 

 narrow antero-posteriorly. Bullae a little larger than in 

 occidentalis, much smaller than in rvfinus. 



Incisors narrow for this group, not even so broad as in the 

 smaller A. occidentalis, of which the type is younger than 

 that of ansorgei. Molars slightly larger than in occidentalis, 

 but all three species, widely as they differ in general size, 

 have the molars of approximately the same dimensions. 



* Cf. Wroughton, Ann. & Mag. Nat. Hist. (7) xvii. pp. 376-377 

 (1906). 



