RODENTS OF LIBYA 241 



feet naked vent-rally with five distinct claws; hind feet large and heavily 

 furred ventrally, Pinkish-Buff with three distinct claws; tail indis- 

 tinctly bicolored Cinnamon-Buff dorsally and Pale Pinkish Buff ven- 

 trally; prominent terminal pinna transversely bicolored Bone Brown 

 proximally and white distally; dark portion of pinna of tail becoming 

 white ventrally. Skull: Large and massive; cheek teeth heavy; 

 zygomata heavy; braincase flattened; auditory bullae moderately in- 

 flated and large; anterior palatine foramina short and wide; lachrymals 

 large; foramen on anterior margin of angular process markedly 

 enlarged. 



Comparisons. Ja cuius jaculus tripolitanicus differs from the type 

 and type series of Jaculus jaculus whitchurchi in larger, more massive 

 skull, relatively, as well as actually, larger, more inflated, auditory 

 bullae, heavier zygomata, wider anterior palatine foramina, larger in- 

 fraorbital foramina, markedly less inflated braincase, and larger 

 cranial and external measurements. In color, J. j. tripolitanicus has 

 a much stronger and more uniform suffusion of dark-tipped hairs on 

 the dorsum, a greater admixture of brownish hairs on flanks, and a 

 more sharply bicolored tail with a much darker anterior portion of the 

 pinna. 



Compared with the type and type series of Jaculus jaculus arena- 

 ceous, J. j. tripolitanicus is larger and more massive in almost all 

 cranial measurements, has more inflated auditory bullae, markedly 

 wider anterior palatine foramina, more divergent pterygoid processes, 

 larger lachrymals, more robust zygomata, and larger, more oval 

 foramina on anterior fossa of angular process of mandible. In color, 

 J. j. tripolitanicus has less admixture of dark-tipped hairs on sides 

 and dorsum, more suffusion of buffy hairs on flanks, a more prom- 

 inently bicolored tail, and a darker anterior portion of the pinna. 



From topotypical Jaculus jaculus jaculus, specimens from Gharian 

 are larger in all cranial measurements and have larger more inflated 

 auditory bullae, a larger foramen magnum, more divergent pterygoid 

 processes, more robust zygomata, less vaulted braincases, larger 

 lachrymals, and more widely flaring nasals. Jaculus jaculus tripol- 

 itanicus also differs from the nominate subspecies in paler dorsal 

 coloration, owing to less admixture of dark-tipped hairs, greater 

 suffusion of buffy hairs on sides and pectoral regions, and more 

 uniformly colored vibrissae. 



In their generally large overall size and massive skulls, members 

 of this subspecies resemble representatives of Jaculus jaculus sejrius 

 from western Algeria but differ in having significantly longer hind 

 feet, much larger ears, and longer molariform toothrows. The simi- 

 larities probably do not indicate close taxonomic relationship, how- 

 ever, because populations of Jaculus jaculus centralis, a subspecies 



