RODENTS OF LIBYA 237 



of nasals 12.2 (11.6-12.8), 12.3 (11.6-12.8), [12.6]; breadth of rostrum 

 at level of antorbital foramina 5 (4.7-5.3), 5 (4.7-5.1), [5.1]; greatest 

 breadth of braincase, 18.2 (17.6-18.6), 18 (17.5-18.4), [18.4]; greatest 

 breadth across antorbital processes 22.7 (22.3-23.1), 22.5 (21.7-23.6), 

 [23.1]. 



Diagnosis. Upperparts Light Ochraceous-Buff with suffusion of 

 darker hairs on rump; all hairs of dorsum Plumbeous basally; rostral 

 circumorbital, mystacial, subauricular, interorbital, and pectoral 

 regions Pale Ochraceous-Salmon; pinna of ear sparsely haired and 

 Clay Color; underparts, flanks, and dorsum of fore and hind feet 

 white, grading to Light Buff in some specimens; lateral vibrissae 

 long and white; median vibrissae smaller and darker; hind feet 

 heavily furred ventrally and Pale Pinkish Buff; palmar surfaces of 

 front feet naked; tail Pinkish Buff dorsally, Light Buff ventrally, 

 with prominent bicolored terminal pinna, Warm Sepia proximally 

 and white distally; encroachment of buffy areas of the sides onto 

 dorsum imparting a decidedly pale aspect to all of the specimens. 

 Skull: Triangular; size medium; molariform teeth medium; auditory 

 bullae moderately inflated; infraorbital foramina large; braincase 

 relatively flattened, rostrum heavy; zygomata convergent anteriorly; 

 pterygoid fossae large and partially enclosed ventrally by the palatines; 

 pterygoid processes long and attenuated; basisphenoids, alisphenoids, 

 presphenoids, and orbitosphenoids markedly reduced and restricted 

 to median plane; lachrymals appearing as a posterior process of the 

 maxillary and situated dorsad of the winglike antorbital processes; 

 lateral margins of basioccipital convergent anteriorly; jugular proc- 

 esses small; distinct foramen located on ventroanterior margin of 

 condyloid process and anterior margin of angular process; coronoid 

 process markedly reduced. 



Comparisons. From the type and the type series of Jaculus jaculus 

 cufrensis, specimens of J. j. collinsi differ in larger size of most cranial 

 characters, being smaller only in the least interorbital breadth and of 

 comparable size in the greatest breadth across antorbital processes. 

 Members of this subspecies also have larger molariform teeth, heavier 

 zygomata, narrower rostra, and less compact skulls. Jaculus jaculus 

 collinsi is paler in color owing to encroachment of the buffy areas of 

 the sides onto the dorsum, less suffusion of dark hairs on the flanks, 

 and the general overall Light Ochraceous-Buff of the back. 



Jaculus jaculus collinsi appears to be most closely related to J. j. 

 jaculus but can be distinguished by longer molariform toothrow, less 

 inflated auditory bullae, larger infraorbital foramina, heavier rostrum, 

 and less vaulted braincase. In color, J. j. collinsi is markedly paler, 

 has greater suffusion of white or cream-colored hairs on the dorsum 

 of the tail, and has less admixture of dark hairs on sides and flanks. 



