10 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 
people, and they may have had little occasion to observe the sea- 
shells which litter the shores of their Mediterranean border, 
although such beautiful genera as Cyprea, Marginella, Bulla, 
Nassa, Dentaliwm, Murex, Mactra, Cerithiwm, &c., are plentifully 
represented. But inland the ground for long stretches is actually 
white with land shells ; it appears sometimes as if beach and dry 
land had exchanged their natural characteristics. This is especially 
the case in the inland sandy deserts, where one unacquainted with 
conchological science might readily make the mistake of supposing 
that the shells, which strew the ground as abundantly as do cockles 
and mussels our own marine shores, were not land molluscs, but the 
remains of marine forms which had existed in some primeval ocean. 
On riding out from Jericho, for instance, towards the Dead Sea— 
a distance of about ten miles—the traveller crosses a great sandy 
plain dotted with miserable, stunted shrubs, which become scarcer 
and scarcer as the margin of the Salt Sea is approached. Yet it is 
just here, round the bases of these shrubs, that the shells are most 
abundant. What the animals get to subsist on is a perpetual 
marvel. Many may be seen hanging on to the withered leaves of 
the shrubs, with their mouths firmly glued by means of their 
calcareous exudations. Often they do dry up and die, but this 
secretion makes them retain their hold of the leaves till the fierce 
desert wind arises and breaks off both branch and molluse. In 
order to protect themselves from the more than tropical heat of 
the valley—even in spring I experienced 100° F. in the shade— 
the animals provide themselves with a singularly thick shell, which 
is at the same time colourless and lustreless. Beauty of outline 
is no part of their programme ; defence against the sun’s rays is 
what they alone seem to desire. 
Of such species, I collected in this quarter large numbers of 
Helix variabilis, Drap.; Helix caperata, Mont.; Helix candidissima, 
Drap., var. hierochuntica, Boiss.; Helix seetzeni, Koch, a species 
of which the sea-gulls of the southern desert are particularly fond ; 
and Helix hierochuntica, Roth, one of the few desert specimens 
not bleached white, but readily distinguishable by its red peristome 
and flattened spire. In addition, one solitary shell caught my eye 
as I was riding past, and dismounting, I secured a specimen of 
what is one of the rarest among the Syrian mollusca. “ Helix 
tuberculosa” (Conrad in Lynch), says Canon Tristram, “is the 
