RODENTS OF LIBYA 169 



At El Gatrun some of these jirds were purchased from the Arab 

 inhabitants and had presumably been living commensally with them. 

 This is not surprising in view of the sandy floors and hastily built 

 structures in which these people live. 



Jirds are primarily nocturnal, but on one occasion at El Gatrun, 

 an old adult male, 322672, was shot in full daylight while it foraged 

 near the base of a clump of palms. 



Gerbillus pyramidum is commonly associated with M. c. amplus 

 in these sandy habitats but is always much more abundant. The 

 smaller Gerbillus gerbillus occurs less frequently with these jirds. 



The name amplus, from the Latin meaning large or largest, refers 

 to the large size of members of this subspecies. 



Meriones caudatus caudatus Thomas 



Meriones libycus caudatus Thomas, Ann. Mag. Nat. Hist., ser. 9, vol.3, p. 267, 

 March 1919 (Tamari-Fergian, Tripolitania, Libya). 



Specimens examined. Thirty-four, from Tripolitania: 40 km 

 ENE, Nalut, 2; 5 km N Mizda, 1 ; 55 km SW Bir Allagh, 19; 5 km E 

 Derg, 6; 2 km SW Hun, 5; Bir Fergian, 1 (skin only). 



Measurements. Averages and extremes of five adult males and five 

 adult females from 55 kilometers southwest of Bir Allagh, are: Total 

 length 282 (268-298), 276.8 (270-282); length of tail 141.4 (130-151), 

 138.8 (135-142); length of hind foot 35.8 (34-38), 33.8 (33-35) ; length 

 of ear 18.4 (17-19), 17.8 (16-19); greatest length of skull 38.7 (37.5- 

 39.7), 38.3 (37.4-39.5); length of palate 15.6 (15.3-16.1), 15.6 (15.3- 

 16); length of audital portion of auditory bulla 14.7 (14-15.7), 14.8 

 (14.3-15.4); alveolar length of upper molariform toothrow 5.3 (4.8- 

 5.5), 5.3 (5.2-5.5); least interorbital breadth 7 (6.8-7.1), 6.8 (6.5- 

 7.3); length of nasals 14.7 (13.8-15.4), 14.7 (14.4-15); breadth of 

 rostrum at level of antorbital foramina 4 (3.9-4.1), 3.9 (3.7-4.1); 

 greatest breadth across zygomatic arches 20.9 (19.9-21.7), 20.5 (20-21). 



Diagnosis. Pelage of dorsum silky and lustrous with long guard 

 hairs projecting beyond shorter underlying buffy hairs; upperparts 

 Cinnamon-Buff grading to Pinkish Buff on sides and flanks; all parts 

 of dorsum strongly suffused with black, being particularly concen- 

 trated on rump; in most specimens, supraorbital and postauricular 

 patches prominent, Pale Pinkish Buff, frequently persisting as in- 

 distinct pale areas anterior to pinnae; eye ring black; circumoral and 

 mystacial areas, cheeks, and chin pure white, in some specimens, with 

 faint suffusion of buff; pinna of ear densely furred, same color as 

 dorsum, with distinct row of buffy hairs along anterior margin; dorsal 

 surfaces of fore and hind feet usually pure white, but, in some speci- 

 mens, with slight suffusion of buff; palmar surfaces naked; plantar 

 surfaces naked proximally, densely furred distally and almost pure 

 white; fore and hind feet each with five digits with claws, the latter 



285-134 O — 68 12 



