FAUNA AND FLORA OF SINAI, PETRA, AND WADY 'ARAB AH. 45 



Tristram's work. This gerbille is a wide-spread desert form, from 

 Candahar to Algiers. The holes of this species, and some others, are 

 surrounded outside, besides being well supplied inside, with little heaps 

 of chopped fragments of plants, leaves, seeds, and other remnants of 

 vegetation. Ant-roads are also conspicuous, about an inch wide, and 

 firmly and smoothly pressed down. 



Porcupine quills and decomposed remains of hedgehogs were several 

 times picked up in the north end of the 'Arabah. 



At 'Aylan Buweirideh sub-fossil shells were obtained in marl deposits 

 at about 1,400 feet above the level of the Dead Sea, or about 100 feet 

 above sea-level. Two of these, Melania tuberculata, Mull. ; Melanopsis 

 Saulcyi, Bourg., have been figured by Professor Hull at page 100 in his 

 work already referred to. I gathered besides these Melanopsis buccinoidea, 

 Oliv., and M. eremita, Trist. These are fluviatile or lacustrine species, and 

 are all found still living round the Dead Sea in various streams and 

 springs. The last-mentioned species is very rare, and I did not find 

 it alive, but Canon Tristram discovered it at the south-western Ghor. 

 These marls, in the opinion of geologists, are remaining deposits of an 

 ancient lake or inland sea, of which the Dead Sea is all that now 

 exists. From where we now stood to near the source of the Jordan, about 

 225 miles northwards, must have been a continuous sheet of water in 

 (geologically speaking) tolerably recent times. 



Lower marls are very characteristic at an average level of 600 feet 

 above the present level of the Dead Sea. I searched these marls for 

 similar remains in many places, but always found them absolutely barren 

 in records of the past, and very rarely inhabited by any existing life, 

 vegetable or animal. Trunks of palms, floated to and then embedded 

 in these marls at the base of Jebel Usdum, form no exception ; since 

 these may have been drifted thither in times which are as yesterday 

 compared with the ' middle marls.' The upper marls are fairly vegetated 

 with the existing flora. The natural conclusion would be that the 

 ancient sea, at first harbouring fresh-water inhabitants, became reduced by 

 a long process of evaporation, or some other cause, to about a mean height 

 between its present and its earliest level, and that it was already so salt 

 that it was almost if not quite uninhabitable. 



At this height, judging from the extent of the middle marls, the waters 



