62 BULLETIN 99, UNITED STATES NATIONAL MUSEUM. 



Specimens from the Sotik (Kabalolot Hill) although rather inmia- 

 ture, are distinctly this species and not T. surdaster polionops, which 

 occurs in the Mau Escarpment. The Sirgoit Lake specimen may 

 possibly represent one of the forms described from Mount Elgon^ 

 which are not otherwise represented in our collection, but the speci- 

 men is preserved in alcohol and is not distinguishable from skins of 

 iheanus. This form evidently blends into TJiamnomys ibeanus lutosus 

 in the Northern Guaso Nyiro country, and specimens from this region 

 are not easil}" placed. There are no specimens m our collection 

 which approach in size the type skull of Thamnomys gigas Dollman, 

 from Kenia. In describmg this species Dollman, as usual, gives no 

 clew to the age of the animal be3''ond the fact that it is ''adult." 

 This may mean anything beyond the condition when the last molar 

 has erupted up to extreme senility, during which period the skull 

 of any murine grows enormously. If the type skuU of "gigas" is an 

 old individual, v/ith much worn teeth, I should suspect the name to be 

 a synonym of ibeanus. 



THAMNOMYS IBEANUS LUTOSUS Dollman. 



1911. Thamnomys surdaster lutosus Dollman, Ann. and Mag. Nat. Hist., ser. 8, 

 vol. 8, p. C57. November. (Mount Nyiro, British East Africa; type in 

 British Museum.) 



Specimens. — Twenty-two, from the following localities: 



British East Africa: Isiola River, 1 in alcohol (Heller); Moimt 



Gargues, 16 (HeUer); Ngare Ndare River, 4 (HeUer); Northern 



Guaso Nyiro, 1 in alcohol (Heller), 



Heller found three large embryos each in females collected at 



Mount Gargues, August 23 and September 1. 



THAMNOMYS DISCOLOR Thomas. 



1910. Thamjiomys discolor Thomas, Ann. and Mag. Nat. Hist., ser. 8, vol. 5, p. 

 283. March. (Kakumega Forest, Kisumu, British East Africa; type 

 in British Museum.) 



Specimens. — Sixty-three, from localities as foUows: 



Uganda: Kampala, 1 (Loring). 



British East Africa: Kaimosi, 62, including 17 in alcohol 

 (Heller, Turner). 



As usual in this genus, there is considerable variation in color 

 among the skins of this series. The presence or absence of dark 

 whisker marks and light supraorbital spots is a matter of individual 

 variation. The type-specimen is described by Thomas as lacking 

 both. 



Heller records three embryos from a female collected at Kaimosi, 

 February 1. 



« Thamnomys surdaster elgonis Thomas, Ann. and Mag. Nat. Hist., ser. 8, vol. 5, p. 282, March, 1910; 

 TTuimiwmys surdaster insignis Dollman, Ann. and Mag. Nat. Hist., ser. 8, vol. 7, p. 528. May, 1911. 



