RODENTS OF LIBYA 247 



are light yellow or russet, and the dorsum is more streaked or marbled. 

 The tail is brownish rust above with some blackish hairs at the tip 

 (6 or 7 cm)." Jaculus o. mauritanicus apparently also has a shorter, 

 wider muzzle, a larger head, smaller ears in proportion to the body, 

 and generally a larger, more robust body. The jerboa from Rumia 

 shows some of these characters, particularly in width or rostrum, 

 streaked and darker dorsum and proportionately smaller ears, but in 

 general body size and in most cranial characters, it is closer to the 

 nominate subspecies and is here so referred. The referral of this 

 specimen from Tripolitania to J. o. orientalis is, however, provisional 

 until such time as adequate series of these large jerboas become 

 available from western Libya and permit a more thorough study. 



The type locality of J. o. orientalis is not firmly fixed but is believed 

 to be somewhere in the mountains separating Egypt from Arabia 

 and thus probably near Sinai. Only one subadult specimen is available 

 from Sinai, however, and thus valid comparisons with jerboas from 

 Libya are not possible. It is doubtful if the large jerboas inhabiting 

 the coastal areas of Sinai, Egypt, and Libya are all of the same 

 subspecies. Setzer (1957) also questioned the occurrence of a single 

 subspecies over such a wide geographical area. 



Local differences in pelage color of these large jerboas are notice- 

 able throughout their range in Cyrenaica. These differences are 

 probably attributable to differences in age, sex, or seasonal change. 

 Much larger series are required to determine the exact taxonomic 

 significance of color in these large jerboas. 



Ecological observations. In Libya, these large jerboas are 

 confined almost exclusively to the more humid environment of the 

 coastal plain. Occasionally, specimens were taken from hamadas 

 farther inland, and on one occasion, in Tripolitania, one was collected 

 from the brink of the coastal escarpment. This species was recorded 

 by de Beaux (1932) from Augila, Cyrenaica Province, at a distance 

 somewhat removed from the coastal plain. The elevation at Augila, 

 however, is relatively low and accordingly the general habitat here 

 is similar to that of the coastal plain. 



These jerboas are difficult to catch by standard trapping procedures 

 and trap yields are usually low. Setzer (1957) was able to obtain 

 the series from Gheminez only by digging the animals from their 

 burrows. At this time, he also obtained several specimens of the 

 four-toed jerboa (Allactaga tetrad a cti/la) . 



On two occasions, adult specimens were picked up some distance 

 from a trapline. Apparently, these animals had been struck on the 

 head by a trap but were able to move some distance before dying. 

 Museum special traps are not of sufficient size to immediately kill 

 and hold animals of this size. 



