134 U.S. NATIONAL MUSEUM BULLETIN 2 75 



brown hairs, being particularly concentrated on rump; subauricular 

 region with strong admixture of blackish hairs; preauricular and post- 

 auricular patches conspicuous and white; eye ring black; mystacial, 

 circumoral, and pectoral areas Light Buff; pinna of ear sparsely haired, 

 Ochraceous-Tawny basally and Mummy Brown distally, and with 

 distinct tuft of grayish hairs on antero ventral margin; vibrissae 

 relatively short and formed from equal numbers of light and dark hairs; 

 forearm with distinct buffy patch and otherwise white throughout; 

 hindlegs with conspicuous Dark Olive patch on ventral surface, 

 otherwise white throughout; fore and hind feet white, each bearing 

 five digits with claws; palmar and plantar surfaces of fore and hind 

 feet entirely naked, the latter Mars Brown in color; underfur of all 

 dorsal pelage Deep Plumbeous; entire underparts white with faint 

 buffy suffusion in some specimens; tail relatively long, distinctly bi- 

 colored, Verona Brown dorsally, almost white ventrally and slightly 

 penicillate. Skull: Small and gracile; auditory bullae small and mildly 

 inflated ventrally; zygomatic breadth narrow and zygomata fragile; 

 braincase slightly vaulted. 



Comparisons. Compared with a single specimen of Gerbillus 

 campestris campestris from near Oran, Algeria, the type and para types 

 of Gerbillus campestris brunnescens are paler in dorsal color, have 

 slightly more tufted tails, much longer tails, more suffusion of dark 

 color around eyes, larger bodies, and cranially are larger and more 

 robust, with wider rostra, wider interorbital breadths, and larger 

 cranial measurements, especially length of the upper molariform 

 toothrow. 



Members of this new subspecies may be distinguished from topo- 

 types of G. c. dodsoni from Ain Hammam, Tripolitania Province, and 

 a large series from Brach, Fezzan Province, by their darker (more 

 brownish) and more uniform dorsal color, longer and markedly less 

 tufted tails, greater overall length of body, slightly shorter ears, less 

 robust skulls, markedly smaller and less inflated auditory bullae, and 

 more vaulted braincases. 



Compared with topotypical G. c. haymani from Siwa Oasis, Western 

 Desert Governorate, Egypt, and a small series representing haymani 

 from Bahr el Tubat, Cyrenaica Province, Libya, G. c. brunnescens is 

 markedly darker in dorsal coloration, has a less tufted tail, smaller 

 hind feet and ears, and a more gracile skull which is markedly smaller in 

 all cranial characters, being closest in the width of the rostrum and the 

 length of the upper molariform toothrow. 



From topotypes of G. c. wassifi from the Libyan Plateau, near Salum, 

 Western Desert Governorate, Egypt, G. c. brunnescens differs in its 

 darker dorsal color, smaller overall size, relatively longer tail, smaller 

 ears, smaller skull, narrower anterior palatine foramina, narrower 



