EAST AFRICAN MAMMALS IN NATIONAL MUSEUM. 117 



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



British East Africa: Archer's Post, 4, including 1 in alcohol 

 and 2 odd skulls (Heller); Chanler Falls, 1 (Percival); Isiola River, 

 1 in alcohol (Heller); Kara River, Marsabit Road, 1 (Heller); Laki- 

 undu River, 21, including 10 in alcohol and 3 odd skulls (Heller); 

 Longaya Water, Marsabit Road, 2 (Heller); Marsabit Road, 1 in 

 alcohol (Heller); Merele Water, Marsabit Road, 1 (Heller); Mount 

 Gargues, 9, including 2 in alcohol (Heller) ; Northern Guaso Nyiro 

 River, 6, including 2 in alcohol (Heller, Percival) ; Quoy, Marsabit 

 Road, 1 (Heller); Salt River, 3 (Percival); Sandai, 1 (Percival). 



Included in the above series are several specimens which have been 

 identified by Dollman as belonging to his Acomys pulcliellus ,^ de- 

 scribed from the same type locality as Acomys ignitus kempi. The 

 specimens are unquestionably the rather immature examples of Icempi, 

 and it seems probable that such a specimen was made the type of 

 pulclieUus. There is an extraordinary difference in size of skulls in 

 this species between young adults and old adults. SkuUs which have 

 the teeth worn so that all pattern is obliterated still have the basal 

 suture open, and the skull apparently grows throughout the life of 

 the animal. It would seem strange that out of all the specimens of 

 this group of Acomys from the Northern Guaso Nyiro in our collec- 

 tion all the oldest should be Icempi and all the youngest specimens 

 pulcheUus. The series contains specimens showing all ages from those 

 in which the last molar is not in place to very old individuals with the 

 teeth almost worn away; and I am well satisfied that all belong to one 

 species. The oldest specimens have heavier and longer spines than 

 young or subadult animals. Mr. Heller examined the type-specimens 

 of kempi and pulcTieUus in London and noted that the teeth were 

 almost unworn in the type skull of pulcheUus, while the type of 

 kempi was old with much more worn teeth. 



Two females from Marsabit Road, July 20 and 21, contained 

 embryos; in one a single fetus, in the other, two fetuses. 



ACOMYS IGNITUS MONTANUS HeUer. 



1914. Acomys ignitus montanus Heller, Smithsonian Misc. Coll., vol. 63, No. 7, 

 p. 12. June 24. (North slope of Mount Marsabit, British East Africa; 

 type in U. S. Nat. Mus.) 



Specimens. — ^Two, as follows : 

 British East Africa: Mount Marsabit (Percival), 

 The type was trapped at an altitude of 4,600 feet on the north 

 slope; the paratype is from the south slope of the mountain. These 



i Ann. and Mag. Nat. Hist., ser. 8, vol. 8, p. 127. July, 1911. 



