96 BULLETIN 99, UNITED STATES NATIONAL MUSEUM. 



guish as a separate subspecies the specimens representing Heller's 

 Leggada naivasJix. Specimens from Kisimbiri and Kikandwa, on the 

 upper Victoria Nile, evidently slightly approach in color Mus tnton 

 fors of Kuwenzori, but are not sufficiently different to separate from 

 triton proper. In this connection it is interesting to note that the 

 aames triton sxnd fors as members of this genus, were published simul- 

 taneously, and triton has only a single line priority. The name /ors 

 is usually cited from the Ruwenzori report,^ with Thomas and 

 Wroughton as its authorities. As a matter of fact it was published as 

 a vaUd name by Thomas in December, 1909, in the description of 

 Leggada triton, where the greatest length of the skull of the type 

 specimen is given. 



MUS TRITON MURILLA (Thomas). 



1910. Leggada triton murilla Thomas, Ann. and Mag. Nat. Hist., ser. 8, vol. 5, p. 

 91. January. (Machakoa, British East Africa; type in British Museum.) 



1910. 3Ius (Leggada) triton murillus Roosevelt, African Game Trails, Amer. ed., 



p. 473; London ed., p. 485. 



Specimens. — Eighteen, from locaUties as follows: 



British East Africa: Fort Hall, 1 (Loring); Kamiti Farm, Athi 

 Plains, 1 (Loring); Kapiti Plains, 12, including 2 in alcohol (Loring); 

 Oljoro O Nyon River, 1 (Loring); Southern Guaso Nyiro River, 1 

 (Loring); Thika River, 2 (Loring). 



This gray form of triton is evidently restricted to the region south 

 of the upper Tana and Athi rivers, extending westward to the Mau 

 Escarpment. It is a very well marked subspecies. 



MUS EMESI HeUer. 



Plate 25. 



1911. Mus musculoides emesi Heller, Smithsonian Misc. Coll., vol. 56, No. 17, 



p. 5. February 28. (Kabula Muliro, Uganda; type in U. S. Nat. Mus.) 



Specimens. — Twenty, from the following localities: 



Uganda: Hoima, 2, including 1 in alcohol (Loring); Kabula MuUro, 

 1 (Loring); Kikanda, 1 in alcohol (Loring); Kikandwa, 4, including 

 1 in alcohol (Loring); Kisimbiri, 8, including 3 in alcohol (Loring); 

 Kisingo, 3 in alcohol (Loring); Nkyanuna, 1 (Loring). 



This white-beUied mouse is clearly related to 31. triton, but must be 

 classed as a full species as it is found ranging with that form at locali- 

 ties in western Uganda. Its range appears to be much more restricted 

 than is the distribution of triton. In size, the skull of emesi is inter- 

 mediate between skulls of triton and those of hellus and gratus. 



For measurements of specimens see page 99. 



1 Trans. Zool. Soc. London, vol. 19, p . 506. March^ 1910. 



