178 U.S. NATIONAL MUSEUM BULLETIN 2 75 



18; occipitonasal length of skull 36.5, 35.9, 35.5; length of palate 15, 

 15.2, 15.1; length of anterior palatine foramina 6.1, 5.7, 5.7; length of 

 audital portion of auditory bulla 14.3, 13.8, 14.4; alveolar length of 

 upper molariform toothrow 5.3, 5.7, 5.2; least interorbital breadth 

 5.7, 5.9, 5.8; length of nasals 13.4, 13.6, 13.6; greatest breadth across 

 zygomatic arches 19.8, 19.3 19.9; breadth of rostrum at level of ant- 

 orbital foramina 3.1, 3.4, 3.4. 



Diagnosis. Pelage of dorsum fine, silky and lustrous; varying in 

 color from Light Ochraceous-Buff and Cinnamon-Buff to Pinkish 

 Cinnamon; most specimens with mild admixtures of brown-tipped 

 hairs on dorsum, which produce a slightly streaked or marbled ap- 

 pearance; sides, supraorbital, preauricular, and subauricular regions 

 with faint suffusions of gray; eye ring black or dark brown; circumoral 

 and mystacial areas, and conspicuous postauricular patches Pinkish 

 Buff; pinna of ear densely haired, about same color as dorsum, and 

 with distinct row of buffy hairs along anterior margin; vibrissae long, 

 formed of black and white individual hairs; forefeet almost pure 

 white dorsally, naked ventrally and with five digits bearing pale- 

 colored claws; hind feet usually white dorsally, with thick covering of 

 hairs ventrally, except for conspicuous hairless areas on proximal 

 halves of plantar surfaces, and also with five digits bearing pale- 

 colored claws; tail relatively short for the species, Pinkish Buff in 

 color, appearing bicolored owing to slight admixture of black hairs 

 dorsally, and with distinct brush of black or dark brown hairs distally. 

 Skull: Relatively small and gracile for the species; auditory bullae 

 large and bulbous, noticeably inflated ventrally, laterally, and poste- 

 riorly, but to a lesser extent than in other subspecies; lateral meatal 

 expansion closely applied to squamous portion of temporal bone; 

 suprameatal triangle large, triangulariform, and imperfectly closed 

 posteriorly by enveloping processes of the supraoccipital and temporal 

 bones. 



Comparisons. From representatives of Meriones crassus crassus 

 Sundevall from the vicinity of Feiran Oasis and St. Catherine's 

 Monastery, Sinai, Egypt, paratypes of Meriones crassus iripolius from 

 Tripolitania and representatives of M. c. tripolius from various localities 

 in the Fezzan differ in darker dorsal color, shorter and less inflated 

 auditory bullae, less robust zygomata, and generally much smaller 

 size of cranium and all external dimensions. 



Compared to representatives of Meriones crassus pallidus Bonhote 

 from the Eastern Desert Governorate, Egypt, M. c. tripolius differs in 

 the same characters as given for M. c. crassus. Adult specimens of 

 M. c. asyutensis Setzer are not available for comparison, but judging 

 from the original description (Setzer, 1961), they are significantly 



