EAST AFRICAN MAMMALS IN NATIONAL MUSEUM. 95 



RATTUS COUCHA DURUM^ (Heller). 



Plate 24. 



1912. Epimys coucha durumse Heller, Smithsonian Misc. Coll., vol. 59, No. 16, 

 p. 9. July 5. (Mazeras, British East Africa; type in U. S. Nat. Mus.) 



Specimens. — Sixty, from localities as follows: 



British East Africa: Changamwe, 9, including 2 in alcohol 

 (Mearns); Maji-ya-chumvi, 3 (Heller); Mariakani, 2 (Heller); Maze- 

 ras, 46, including 7 in alcohol (Heller). 



The specimens of this subspecies average much grayer in color than 



those of the nearly related R. c. Jiildehrandtii. Breeding records are 



noted on labels of females from Mazeras as follows: December 22, 



seven embryos; December 23, eight embryos; December 24, eleven 



large embryos. 



Genus MUS Linnaeus. 



1758. Mus Linnaeus, Syst. Nat., ed. 10, vol. 1, p. 59. (M. musculus.) 



Curiously enough the common house mouse (Mus musculus) is not 

 represented in our British East African collections. The native 

 species of the genus have so far, it would seem, held their territory 

 from this invader. 



For detailed measurements of specimens of Mus see pages 98-101. 



MUS TRITON TRITON (Thomas). 



Plate 24. 



1909. Leggada triton Thomas, Ann. and Mag. Nat. Hist., ser. 8, vol. 4, p. 548. 



December. (Kirui, Elgon, British East Africa; type in British Museum.) 



1910. Leggnda naivashx Heller, Smithsonian Misc. Coll., vol. 54, [No. 1924], 



p. 2. February 28. (Base of Aberdare Mountains, eastern edge of Naiva- 

 sha Plains, British East Africa; type in U. S. Nat. Mus.) 

 1910. Mus (Leggada) triton naivashse Roosevelt, African Game Trails, Amer. 

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



Specimens. — Two hundred and sixteen, from the following locahties: 



Uganda: Kikandwa, 3, including 1 in alcohol (Loring); Kisimbiri, 

 2 (Loring). 



British East Africa: Aberdare Mountains, 5, including 1 in alcohol 

 (Heller); Burgunett Kiver, Meru Road, 1 (Heller); Fort Hall, 1 in 

 alcohol (Loring); Isiola River, 1 (Heller); Kaimosi, 51, including 28 

 in alcohol (Heller); Kakumega, 6 (Heller); Kibabe, Kisumu, 1 

 (Heller) ; Lake Naivasha, 27, including 5 in alcohol (Loring) ; Lukosa 

 River, 5, including 2 in alcohol (Heller) ; Mission, Kisumu, 1 (Heller) 

 Mount Kenia, west side, 46, including 31 in alcohol (Loring, Mearns) 

 Nyangnori, 1 (Heller) ; Nyeri, 36, including 25 in alcohol (Loring) 

 Nyuku River, Meru Road, 1 in alcohol (Heller); Nzoia River, Guas 

 Ngishu Plateau, 8, including 6 in alcohol (Heller); Wambugu, 20, 

 including 6 in alcohol (Loring) . 



There is much purely individual variation in the amount of black- 

 ish on the feet and tail. I can find no characters by which to distin- 



