RODENTS OF LIBYA 127 



of the ear and eye; rostral and circumoral areas Light Buff; pinna 

 sparsely haired and with small tuft of buffy hairs on anteroventral 

 margin; inner surface of pinna Ochraceous-Buff basally, becoming 

 darker distally and on outer surface approaching Light Grayish Olive; 

 vibrissae relatively short and formed of both light and dark hairs; 

 dorsal surfaces of forelegs, hindlegs, feet, and entire underparts white, 

 the latter, in some specimens, lightly suffused with Buff; fore and hind 

 feet each with five digits bearing claws; palmar and plantar surfaces 

 naked, the latter with six metatarsal tubercles; tail relatively long for 

 the species, sparsely haired with short, hispid hairs, moderately 

 tufted terminally, and in most specimens, distinctly bicolored Hair 

 Brown to Wood Brown dorsally and ranging from Light Buff to almost 

 white ventrally; the dorsum of the tail appears particolored owing to 

 the interspersion of light and dark hairs and to exposure of the pale 

 ground color from beneath; this variegated character of the tail is 

 typical. Skull: Relatively large and robust; auditory bullae markedly 

 large, bulbous and inflated ventrally; basioccipital narrow and rod- 

 shaped anteriorly, thus forming distinct elliptical posterior lacerated 

 foramina between it and the auditory bullae; anterior palatine 

 foramina short and rectangular; zygomata relatively heavy with 

 tendency to bow outward posteriorly; braincase moderately domed. 



Comparisons. Near topotypes of Gerbillus amoenus vivax from 

 Goddua, Fezzan Province, Libya, differ from two topotypes of 

 Gerbillus amoenus amoenus (de Winton) from El Aiyat, Mit Riheina, 

 Giza Province, Egypt, in having larger and more robust skulls, 

 noticeably larger, more bulbous and more ventrally inflated auditory 

 bullae, heavier zygomata, wider zygomatic breadth, slightly larger 

 molariform teeth, and longer nasals. Specimens from Libya are also 

 paler in dorsal color, larger in total length, and have longer and slightly 

 more tufted tails. 



Cranially, representatives of G. a. amoenus from Wadi Natroun, 

 Western Desert Governorate, Egypt, are appreciably larger than the 

 two topotypes from Giza Province and are comparable to specimens 

 of G. a. vivax but differ in having shorter and less tufted tails and 

 markedly smaller and less inflated auditory bullae. Another large 

 series of G. a. amoenus from near Faiyum, Egypt, has the smallest 

 auditory bullae of any of the specimens examined from Egypt and, 

 in this character alone, can easily be distinguished from those of 

 G. a. vivax from Libya. 



This subspecies resembles Gerbillus nanus nanus Blanford from 

 Kerman Province, Iran but can be distinguished from the latter by 

 much shorter tail, lighter (less grayish) dorsal color, smaller cranial 

 size, noticeably smaller anterior palatine foramina, and markedly 

 smaller and less inflated auditory bullae. 



