42 BULLETIlSr 99, UXITED STATES NATIOISTAL MUSEUM. 



They inhabited all of the open grassy plots in the bamboo belt and in the open timber. 

 The 'boys' snared many in nooses ingeniously placed in the runs that were opened 

 and closed after the trap was set. \Miile digging into the burrows, several times I 

 found bulky nests of dried grass in side pockets just off the main runway. Most of them 

 were empty, but one was filled with the animals' droppings. 



This large, fluff3^-haired mole-rat is obviously closeh'' related to 

 Tacliyoryctes audax of the Aberdare Range, but exceeds the latter 

 greatly in dimensions. The colors are much the same in the two spe- 

 cies, but adult skulls of rex are very much larger than skulls of audax. 

 There is more than ordinar\- difference in size of skulls of the sexes; 

 female skulls are much smaller. Young examples are usually quite 

 blackish and often have irregular blotches of white on the under- 

 parts. Loring records a female with one large embryo, October 5. 

 Doctor Mearns notes the color of the iris as dark grayish brown. 



The excellent series of forty-seven skulls of this species shows to 

 good advantage the change in size of the teeth with age. A long 

 suite of skulls having been laid out according to age, as judged by 

 various characteristics of the skull and teeth, it is seen that there is a 

 great change in the crown area of the molars during the animal's life. 

 At first the actual crown area is small; it gradually increases in size 

 with wear until a maximum is reached at about the time the external 

 reentrant angle disappears from the pattern. There is then a gradual 

 decrease in crown area; when old age is reached the size of the tooth 

 again appears to be about as in the young adult period. In describing 

 new forms as "smaller toothed" or "larger toothed," material 

 should be compared with specimens of exactly the same age. 



TACHYORYCTES SPALACINUS Thomas. 



1909. Tacliyoryctes spalacinus Thomas, Ann. and Mag. Nat. Hist., ser. 8, vol. 4, p. 

 547. December. (Embi, near Mount Kenia, IJritish East Africa; type 

 in British Museum.) 



Specimens. — Forty-one, from localities as follows: 

 British East Africa: Nyeri, 1 (Loring); two day's journey east 

 of Nyeri, 1 (T. Roosevelt); Wambugu, 39, including 1 in alcohol 

 {Loring, Mearns). 



As in related species all skins of very young animals in this series 

 are wholly black. There is little or no average difference in the 

 color of the sexes in our series of spalacinus; the species differs in this 

 respect from all other forms of Tachyoryctes represented in the United 

 States National Museum collection. The species is a handsome one, 

 rich and dark in color. The skin of one old adult male is entirely 

 black, like the skins of young animals. A conspicuous specific skull 

 character is found in the upper incisors, which protrude far forward. 



Mearns records the mammse as ^ — ^^^ — ^ = 4 pairs. 



^ U w 



