EAST AFRICAN MAMMALS IN NATIONAL MUSEUM. 123 



DASYMYS HELUKUS NIGRIDIUS HoIIister. 



Plate 34. 



1916. Dasymys helukus nigridius Hollister, Smithsonian Misc. Coll., vol. 66, 

 No. 10, p. 2. October 26. (Lake Naivasha, British East Africa; type 

 in U. S. Nat. Miis.) 



Specimens. — Twenty-six, as follows: 



British East Africa: Aberdare Range, 1 (Heller) ; Lake Naivasha, 

 25, including 6 in alcohol and 3 odd skulls (Loring, Mearns). 



This large, dark form is conspicuously different in coloration from 

 its much paler geographical neighbors, D. Ji. Jiclukns and T). h. 

 savannus. The single specimen from the Aberdares, while slightly 

 smaller than Naivasha skins, is fully as dark and is quite unlike the 

 more reddish or brownish-gray specimens of savanvus from the 

 western slopes of Mount Kenia. It was collected at an altitude of 

 7,000 feet. 



The skull of Dasymys helukus nigridius averages somewhat larger 

 than skulls of either Dasymys li. Tielulcus or D. h. savannus, with 

 higher sinciput, heavier rostrum, and greater interorbital breadth. 

 The teeth are also larger. Skins of young animals, about one-half 

 grown, are especially dark as compared with the young of D. h. 

 savannus of corresponding age. The subspecies is further con- 

 spicuous for its very long and silky fur, 



Loring found three large embryos in a female collected at Naivasha 

 Station, August 20. 



DASYMYS ORTHOS HeUer. 



Plate 34. 



1911. Dasymys orthos Heller, Smithsonian Misc. Coll., vol. 56, No. 17, p. 13. 



February 28. (Butiaba, Albert Nyanza, Uganda; type in U. S. Nat, 



Mus.) 

 1914. Dasymys sp. Frick, Ann. Carnegie Mus., vol. 9, p. 8, pi. 1. June 6. 



Specimens. — Three, from localities as follows: 

 Lado: Rhino Camp, 1 (Loring). 

 LTganda: Butiaba, 2 (Loring). 



DASYMYS BENTLEY^ MEDIUS Thomas. 



1906. Dasymys medius Thomas, Ann. and Mag. Nat. Hist., ser. 7, vol. 18, p. 143. 



August. (Mubuku Valley, East Ruwenzori, Uganda; type in British 



Museum.) 

 1910. Dasymys viedius Thomas and Wroughton, Trans. Zool. Soc. London, vol. 



19, p. 514. March. 



Specimen. — One, as follows: 



Uganda: Mubuku Valley, East Ruwenzori (Dent). 



