58 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



THAMNOMYS SURDASTER POLIONOPS Osgood. 



1910. Thamnomys surdaster polionops Osgood, Field Mus. Nat. Hist., Pub. Zool., 

 vol. 10, No. 2, p. 8. February. (Ulukenia Hills, British East Africa; 

 type in Field Mus. Nat. Hist., Chicgao.) 



1910. Thamnomys surdaster polionops Roosevelt, African Game Trails, Amer. 

 ed., i)p. 473, 478; London ed., pp. 485, 489. 



Specimens. — Seventy-two, from localities as follows: 



British East Africa: Engare Narok River, 4 (Loring); Kamiti 

 Farm, Athi Plains, 2 (Loring); Kapiti Plains, 3 (Loring); Kitanga, 

 2 (Mearns); Mount Mbololo, 48, including 21 in alcohol (Heller); 

 Mount Umengo, 8 (Heller) ; Oljoro O Nyon Eiver, 2 (Loring, HeUer) ; 

 Oni, 1 (Loring); Wambugu, 2 (Loring). 



Specimens from the Taita Hills (Umengo and Mbololo) appear 

 to be somewhat intermediate between typical polionops and the 

 Kilimanjaro form which has been referred to surdaster, but they are 

 clearly nearest to polio7iops and are best placed with that subspecies. 

 The cheeks and sides are considerably less richly colored than in 

 the Kilimanjaro specimens. Specimens from the Mau Escarpment 

 (heads of Oljoro O Nj^on and Engare Narok Rivers) are inseparable 

 from examples of typical polionops. The Athi Plains skins have 

 longer tails than usual, but are otherwise typical. 



Heller found three embryos each in females collected at Mount 

 Mbololo, November 5; and Mount Umengo, November 13. Half- 

 grown young were taken at the same dates. Loring caught speci- 

 mens of this commonly arboreal rat "in grass and under rocks in 

 center of prairie land three miles from water." Heller notes trapping 

 it both in trees and on the ground. 



THAMNOMYS SURDASTER UTTORALIS HeUer. 



Plate 18. 



1912. Thamnomys dolichtirus littoralis Heller, Smithsonian Misc. Coll., vol. 59, 

 No. 16, p. 10. July 5. (Mazeras, British East Africa; type in U. S. 

 Nat. Mus.) 



Specimens. — Two, as foUows: 

 British East Africa: Mazeras (Heller). 



This race differs conspicuously from T. s. polionops by its almost 

 pure white feet. 



THAMNOMYS IBEANUS IBEANUS Osgood. 



1910. Thamnomys iheanus Osgood, Field Mus. Zool. ser., vol. 10, No. 2, p. 8. 



February. (Molo. British East Africa; type in Field Mus. Nat. Hist., 



Chicago.) 

 1914. Thamnomys sp. Cockerell, Miller, and Printz, Zool. Anz., vol. 44, 



p. 439; fig. 10, p. 440. June. 



Specimens. — Twenty, from localities as follows: 



British East Africa : Aberdare Mountains, 1 (HeUer) ; Burgunett 

 River, Meru Road, 1 (Heller); Kabalolot Hill, 4 (Heller); Nai- 

 vasha, 13 (Loring); Sirgoit Lake, 1 in alcohol (Heller). 



