RODENTS OF LIBYA 89 



locality and have lighter colored, less prominent tufts on the tail. 

 The common "golden" color phase is also apparently not present in 

 these gerbils from Rumia. "In contrast, the series from 25 kilometers 

 north of Gharian consists almost exclusively of gerbils having this 

 "golden" color. Animals from near Gharian also are wider across the 

 zygomatic arches and have larger molariform teeth. In the aggregate, 

 however, many morphological characters are common to all these 

 different populations and serve to unite them into a single subspecies. 



Setzer (1957) assigned a single specimen (no. 302102) from 5 

 kilometers west of El Agheila, Cyrenaica Province, to Gerbilhis 

 pyramidum aureus ( = Gerbilhis aureus aureus). This specimen resem- 

 bles Gerbilhis aureus in color and general size but in the prominent 

 tufted tail and all other cranial and external characters, it is typical 

 of Gerbilhis pyramidum to which it is here referred. 



Ecological observations. The specimens from near Rumia and 

 Chicla were taken near the brink of the coastal escarpment. The 

 habitat here consists of gently rolling valleys and depressions with 

 rather dense vegetative cover consisting of a wide assemblage of 

 close-growing perennial and annual species. The ground in this area 

 is quite rocky, and the soil has a clay or sandy base. Shallow deposits 

 of smooth sand and small dunes are present, but these are of rare 

 occurrence. The collecting site north of Gharian is located on the 

 coastal plain where large, permanently vegetated dunes are present. 

 I have not visited the type locality near Zliten, but presumably the 

 habitat resembles that near Gharian. 



Gerbillus aureus favillus Setzer 



Gerbillus -pyramidum favillus Setzer, Proc. Biol. Soc. Wash., vol. 69, pp. 179-180, 

 Dec. 31, 1956 (2 km E Sirte, Tripolitania Province, Libya). 



Specimens examined. Twenty, from Tripolitania: 5 km E Sirte, 

 8; 2 km E Sirte, 12. 



Measurements. Averages and extremes of 7 males and 13 females 

 from the above localities are, respectively: Total length 226.1 (216- 

 240), 220.1 (210-236); length of tail 125.7 (119-135); 119.3 (110-132); 

 length of hind foot 30.4 (30-31), 30.3 (30-31); length of ear 14.4 

 (13-15), 13.6 (13-15); occipitonasal length of skull 29.7 (29.3-30.5), 

 29.4 (28.4-30.1); length of auditory bulla 10.5 (10.3-10.8), 10.5 

 (10.3-10.9); crown length of upper molariform toothrow 4.1 (4.1-4.2), 

 4.2 (4-4.3); greatest breadth across zygomatic arches 15.5 (15.1-16.6), 

 15.7 (15.2-16.3); least interorbital breadth 5.8 (5.5-6), 6 (5.7-6.2); 

 breadth of rostrum at level of antorbital foramina 3.2 (3-3.3), 3.2 

 (3.1-3.4); greatest length of nasals 11.4 (11-12), 11.3 (10.4-13.1). 



Diagnosis. Upperparts uniformly Clay Color becoming paler on 

 sides and with admixture of brownish hairs on back; post auricular 



285 134 O — <",s 7 



