NO. lO NEW MURINE RODENTS FROM AFRICA HOLLISTER 3 



Remarks. — This is the largest of the British East African forms of 

 Dasymys. It is further distinguished by its very dark color (almost 

 blackish in some lights), long, silky pelage, and larger skull and teeth. 

 Skins of young, about half-grown animals, are especially dark as 

 compared with the young of Dasymys h. savannus. 



MUS BELLUS PETILUS, subsp. nov. 



Type from Southern Guaso Nyiro River, Ijritish East Africa. 

 No. 162397, U. S. National Museum, skin and skull of male adult 

 (teeth much worn), collected June 28, 1909, by J- Alden Loring. 

 Orig. No. 6450. 



SuhspeciHc characters. — Like Mus belltis bellus (Thomas) of 

 Machakos, but with smaller, more slender skull. 



Measurements of type specimen. — Head and body, 54 ; tail ver- 

 tebrae, 44; hind foot, dry, without claws, 12.3. Skull: Condylobasal 

 length, 16.1 ; zygomatic breadth, 8.4; breadth of braincase, 7.9; 

 length of nasals, 7.0 ; length of mandible, 9.8 ; upper tooth row, 

 alveoli, 2.9. 



Specimens examined. — Three from the Southern Guaso Nyiro and 

 one from Naivasha. 



Remarks. — Compared with large series of specimens of the neigh- 

 boring form, Mus bellus bellus, the specimens of the new subspecies 

 petilus are sharply distinguished by their small, slender skulls. The 

 color of the skins is as in true bellus, and therefore is very dififerent 

 from the color of M. b. vicinus and M. b. enclavce, both of which have 

 larger skulls, like true bellus. 



