246 U.S. NATIONAL MUSEUM BULLETIN" 2 75 



populations agree closely in color, but specimens from Gheminez 

 have slightly less admixture of dark hairs on the rump. 



Compared to a near topotype (BM, no. 12.6.12.170), of Jaculus 

 orientalis mauritanicus Duvernoy from Guelt es Stel, Central Plateau, 

 Algeria, and a specimen (BM, no. 25.6.3.8) representing J. o. mauri- 

 tanicus from near Sfax, Tunisia, the Libyan specimens are more 

 uniformly colored dorsally, have less suffusion of Ochraceous-Salmon 

 on the sides and flanks, are somewhat smaller in total length and 

 length of tail, have narrower and longer rostra, and are slightly 

 smaller in the length of skull. 



Jaculus orientalis, in Egypt and Libya, although resembling Jaculus 

 blanfordi (Murray) in some superficial characters, differs markedly in 

 all of the salient features. Specimens of the latter species as known 

 from Majan (50°02' E, 32°35' N), Dasht-i-lut, and near Jangal, 

 Khurasan Province, Iran, differ from those of J. orientalis from 

 Gheminez in smaller size of every cranial and external measurement. 

 Jaculus blanfordi also differs from J. orientalis in darker, more uni- 

 form dorsal color, more distinctly bicolored tail, less buffy sides 

 more heavily washed with gray, smaller terminal spines on baculum, 

 darker vibrissae, whiter underparts (as opposed to Pale Pinkish Buff), 

 proportionately larger front feet and claws, and darker, almost black, 

 proximal portion of pinna of tail. Cranially, J. blanfordi has a more 

 flattened skull, proportionately more fragile zygomata, smaller molari- 

 form teeth, relatively larger and more inflated auditory bullae, and 

 two, rather than one, distinct, oval foramina in the angular process 

 of the mandible. 



Remarks. An adult male, 325835, from 20 kilometers east of Rumia, 

 Tripolitania Province, differs significantly from the series from Mersa 

 Matruh and other specimens from Libya, in that it is much darker 

 dorsally with markedly stronger admixture of dark hairs, resulting in 

 a streaked or marbled appearance. The sides and pectoral areas are 

 more heavily suffused with Ochraceous-Salmon. Cranially, this speci- 

 men from Tripolitania differs from typical Jaculus orientalis orientalis 

 in having a wider rostrum, smaller lachrymals, narrower anterior 

 palatine foramina, larger foramen in angular process, longer cheek 

 teeth with more laterally directed occlusal surfaces, and lateral 

 margins of antorbital processes more abruptly curved. 



In the above characters, this specimen from near Rumia shows 

 intergradation with Jaculus orientalis mauritanicus, whose range in- 

 cludes northern Algeria and Morocco. No topotypical specimens of 

 the latter subspecies are available for study, but Loche (1867, pp. 

 98-99) gives the following description: "The jerboa of Mauritania 

 is very large, very powerful and darker in color (more russet) than 

 the jerboas of Tripoli. The underparts, the throat, and the extremities 



