194 Annals of tlic South African Museum. 



This genus contains animals allied to the Gerbilles, distinguished 

 by their short tails and their peculiarly shaped skulls in which the 

 tympanic bulla is enormously swollen and enlarged so that it projects 

 back behind the level of the occipital condyles and can be seen at 

 the two posterior angles of the skull when viewed from above. The 

 antorbital plate is not nearly so well developed as in Gerbilles. 



The incisors are very slender and pale and marked with an 

 inconspicuous furrow ; the molars are much reduced in size as 

 compared with those of Gcrbillus. 



Only two species are recognised in this genus the South African 

 one, below described, and P. duprasi, from North Africa. 



PACHYUKOMYS AUEICULAEIS, THE NAMAQUALAND GERBILLE. 



Gerbillus auricularis, A. SMITH, S. Air. Quart. Journ., ii., p. 160 

 (1834); ID., Illustr. Zool. S. Afr. Mamm., pi. xxvi. (1849); DE 

 WINTON, Ann. Mag. N. H. (7), i., p. 5 (1898). 



Gerbillus brevicaudatus, F. CUVIEK, Trans. Zool. Soc., ii., p. 144, 

 pi. xxvi., figs. 10, 13 [Skull] (1836). 



Pacliyuromys auricularis, HUET, Le Naturaliste, i., p. 339 (1881) ; 

 THOMAS, Proc. Zool. Soc., p. 265 (1882) [Damaraland] . 



Description. Form short and thick ; general colour above tawny 

 brown, mottled and pencilled with dull black, the sides somewhat 

 lighter; fur slaty at the base, ochraceous yellow in the middle, and 

 dark brown at the tips ; sides of the muzzle, eyebrows, sides of the 

 head, beneath from the chin backwards, and fore legs pure white ; 

 tarsus covered below with white hairs and provided with a single 

 large somewhat complicated pad occupying the space between the 

 toes ; toes short, claws small and pale yellow in colour ; behind the 

 ear at the base a conspicuous white spot ; ears small, oval, and 

 flesh-coloured, a few white hairs on the inner surface ; tail short and 

 thick, covered with short, stiff hairs, above brown, beneath reddish 

 white. 



Incisors pale yellow, the upper ones grooved rather faintly. 



Dimensions (from a specimen in alcohol). Head and body 4'0 ; 

 tail 3-12 ; hind foot -86 ; from ear to nose-tip 1-12 ; skull, length 1-27, 

 breadth '80 ; upper cheek teeth -18. 



Distribution. The original specimen, described by Smith, came 

 from the Karniesberg in Namaqualand ; it is also recorded from 

 Otjimbique, in Damaraland, and the neighbourhood of Kimberley ; 

 the South African Museum has recently received specimens from 

 near Douglas just north of the Orange River in Griqualand West. 



