222 



U.S. NATIONAL MUSEUM BULLETIN 2 75 



3. ~=i 



Figure 49. — Distribution of the subspecies of Jaculus deserti. 



Comparisons. Representatives of Jaculus deserti can be distin- 

 guished from those typical of Jaculus jaculus by their darker color 

 of sides and dorsum and soles of hind feet, smaller and more compact 

 skulls, larger and more inflated auditory bullae, and the presence of 

 two distinct foramina of comparable size in the angular process of 

 the mandible. 



From Jaculus orienialis, J. deserti differs in smaller size of body 

 and cranium, absence of terminal spines of baculum, slightly lighter 

 coloration of dorsum, and the presence of two distinct foramina in 

 the angular process of the lower jaw. 



Remarks. Jaculus deserti was originally described as a full species, 

 Dipus deserti (Loche, 1867). Subsequently, this species was relegated 

 to a subspecies of the more widely distributed Jaculus jaculus (Eller- 

 man and Morrison-Scott, 1951). 



In the past, the small jerboas of Libya were thought to be rep- 

 resented by two subspecies, J. j. jaculus and J. j. deserti, with 

 large geographic ranges ascribed to each. The range of J. j. jaculus 

 was confined to Egypt, Palestine, Arabia, and eastern Libya, and 

 that of J. j. deserti included Algeria, Tunisia, and central and western 

 Libya. Jaculus jaculus deserti was distinguished from the nominate 



