280 Mr. W. H. Osgood on 



white .area occupying slightly more than half the length of 

 the tail instead of scarcely one fourth. 



Several recently collected specimens from Senegal agree 

 with the type of gambianus in the proportion of light and 

 dark on the tail and may safely be regarded as typical of the 

 species. They indicate typical gambianus to be markedly 

 different from the rich dark-coloured forms like poensis and 

 dolichops. They are, in fact, the most greyish of the whole 

 gambianus group and have the feet most extensively whitish. 



Cricetomys gambianus dolichops, subsp. n. 



Type from Como River, 70 miles from Gaboon, French 

 Congo, West Africa. No. 97. 7. 1. 16, British Museum. 

 Adult male. Collected February 25th, 1897, by (Jr. L. Bates. 

 Original No. 155. 



Characters. — Darkest of the gambianus group; middle of 

 back deep vandyke-brown, the hairs scarcely paler at the 

 base than at the tip ; proximal two-thirds of tail dark brown, 

 terminal third white ; underparts entirely pure white, very 

 sharply contrasted with dark upperparts ; white of under- 

 parts broadly extended on lower cheeks; facial region, fore- 

 head, and nape quite as dark-coloured as back; sides some- 

 what paler, approaching broccoli-brown. 



Skull exceedingly elongate; rostrum very long, slender, 

 and dorsally convex; teeth and audital bullae small; palate 

 smoothly rounded behind, without any indication of a spine ; 

 zygomatic plate rather broad and forward ly projected. 



Measurements. — Type: total length 850 mm.; head and 

 body 420; tail-vertebrae 430; hind foot (s. u.) 71 ; ear 38. 

 Skull of type : greatest length 80'2 ; basilar length 66"9 ; 

 zygomatic breadth 32'9 ; nasals 34'3; least interorbital 

 breadth 10*4; postpalatal length 27'5; diastema 27*8; 

 palatine slits 7 5; maxillary tooth-row 10. 



Bema>ks. — Landana, the type locality of Rochebrune's 

 Cricetomys dissimilis lies about halfway between that of the 

 present form and that of C. g. ansorgei of Angola. Until 

 specimens are obtained from this locality some doubt may 

 attach to both ansorgei and dolichops, although the known 

 variability of the group makes it extremely probable that 

 Rochebrune's species will prove different from both. C. g. 

 dolichops is most closely allied to P. g. poensis, from which it 

 differs chiefly in its very elongate skull without a palatal 

 spine. 



Cricetomys gambianus dichrurus } subsp. n. 



Type from Agoulene, Anambara River, South Nigeria, 

 West Africa. No. 5. 12. 1. 21, British Museum. Adolescent 



