88 U.S. NATIONAL MUSEUM BULLETIN 275 



Diagnosis. Members of this subspecies show pronounced variation 

 in dorsal color, which ranges from uniform, brilliant Ochraceous-Buff 

 in some specimens to more subdued Tawny-Olive in others. This 

 darker color results from a strong admixture of dark-tipped hairs. 

 These darker specimens are characterized as follows: Mystacial, 

 rostral, and circumoral areas and supraorbital patch Light Buff; post- 

 auricular region Clay Color heavily suffused with black; eye ring 

 black; pinna of ear dark distally (Hair Brown) with fringe of buff- 

 colored hairs on anterior margin; anteromedial surface of pinna Cin- 

 namon-Buff; vibrissae short, with occasional dark hairs; lateral 

 surface of forearm with buffy patch; fore and hind feet and legs 

 densely haired dorsally and ventrally and each bearing five digits with 

 claws; tail relatively long and indistinctly bicolored Cinnamon-Buff 

 dorsally and Light Ochraceous-Buff ventrally, becoming more sub- 

 dued distally and appearing Light Ochraceous-Buff; terminal pencil 

 relatively reduced and Hair Brown; entire underparts white. The 

 lighter, more brilliantly colored specimens have white rostral, mysta- 

 cial, and circumoral areas, much lighter vibrissae, more distinct 

 postauricular patches, a smaller supraorbital patch, more conspicu- 

 ously bicolored tails, and lack the buffy patch on the forearm. Skull: 

 Medium in size, somewhat gracile and narrow in dorsal aspect; 

 upper molariform toothrow relatively short and individual teeth 

 small; anterior palatine foramina large; auditory bullae small and 

 ventrally inflated; zygomatic arches almost parallel to orbital surface. 



Comparisons. From the type series of Gerbillus aureus favillus, 

 Gerbillus aureus aureus differs in larger size and larger cranial measure- 

 ments, being comparable in crown length of upper molariform tooth- 

 row, least interorbital breadth and breadth of rostrum at level of 

 antorbital foramina. In color, G. a. aureus is darker and more varied 

 in dorsal color and has a markedly more distinct and darker penicillate 

 tail. Members of the nominate subspecies have more parallel tooth- 

 rows, more ventrally inflated auditory bullae, relatively longer poste- 

 rior palatine canals, and the zygomatic arches are parallel rather than 

 bowed medially. Setzer (1956) used most of the foregoing characters 

 to separate these two subspecies but stated that the skulls of animals 

 of these two subspecies Mere of comparable size. The present study, 

 however, shows that representatives of G. a. aureus are significantly 

 larger in almost all cranial measurements. 



For comparison with Gerbillus aureus nalutensis, see account of 

 that subspecies. 



Remarks. This subspecies apparently represents a genetically 

 heterogeneous group, and the component populations represent a 

 rather broad assemblage of morphological patterns. Specimens from 

 the vicinity of Rumia are slightly darker than those from the type 



