490 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



Remarks: Ellerman (1941, p. 509) lists the names burtoni, pygargus, 

 and dongolanus as synonyms of the nominate form. It seems odd that 

 other kinds of gerbils tend to form subspecies over this same area 

 and yet this species does not. 



When specimens from the Sudan are compared to topotypes from 

 Giza, there is a decidedly lighter color which becomes progressively 

 lighter as the Red Sea coast is approached. The animals from the 

 Red Sea coast area have, in general, narrower molars than the tj'^pical 

 animals but certain few have the teeth as large. 



In specimens from Dongola, topotypes of dongolanus show no 

 appreciable differences from typical pyramidum except in the narrow- 

 ness of the molars. 



A single specimen from Port Sudan is perhaps indicative of an 

 undescribed species in that the auditory bullae are expanded beyond 

 all proportion for pyramidum and the color of the pelage is markedl}^ 

 darker. 



The specimens from Tagbo Hills and from Jebel Meidob are far 

 paler in color than any other specimens seen. The skulls, however, 

 agree with animals from other localities. 



It is not possible, at this time, to tell whether or not one is dealing 

 with several subspecies or merely clinal variation of a single sub- 

 species occupying a vast geographic range. Material from inter- 

 mediate localities is needed to clarify this problem. It seems rather 

 probable that there is more than one subspecies concerned in the area. 



Gerbillus rosalinda St. Leger 



Gerbillus rosalinda St. Leger, Ann. Mag. Nat. Hist., ser. 10, vol. 4, p. 295, Septem- 

 ber 1929. (Abu Zabad, 145 km. southwest of El Obeid, Kordofan.) 



Specimens Examined: Four, all in BM, from: Abu Zabad. 



Measurements: No external measurements are available, but the 

 skull of an adult male from Abu Zabad measures as follows : Greatest 

 length of skull 31.8; condyloincisive length 27.4; length of anterior 

 palatine foramina 5.2; crown length of upper molar series 3.9; length 

 of auditory bullae 11.4; least interorbital width 5.6; length of nasals 

 13.1; width of rostrum at level of antorbital foramen 3.3; greatest 

 breadth of skull 15.5. 



Remarks: The color of the above specimens is a dark reddish 

 brown with the white reduced markedly on the sides, cheeks, and 

 supraorbital and postauricular spots. The color of the back is car- 

 ried on to the dorsal surface of the tail until the black hairs of the 

 brush begin. The brush occupies the distal one-third of the tail. 



In size, G. rosalinda closely approaches G. pyramidum, but because 

 of the smallness of the teeth, the conformation of the anterior palatine 

 foramina, and the pterygoid structure it is retained as a separate 

 species for the present. 



