APPARENTLY CORRELATED TO THE CONDITIONS OP LIFE. 313 
certainty as to tlie conditions wliicL have prevailed in it for any length of time, heyond 
the fact tliat it has always been a large sliallow lagoon, and tl)at a large fpiantity of 
fresh water from the Nile has been ponred into it every year. 
I did not find any live Cochles in it, and am disposed to believe that they are extinct 
in it, having probably died iji consec^nence of some of the sndden changes which have 
befallen the lake. 
The shells found on the Ijanks of Mareotis are, like those of Abu Kir, of two 
kinds :— 
Rough map of Lake Mareotis, together with Abu Kir and the three Ramleh lakes. 
(1.) Old shells, for the most part very large and not greatly differing from the 
“ great shells ” of Abn Kir. These occur especially on the cliffs near the road running 
Iteside the lake on its south-west shore. The shells here occur at a level several feet 
above that of the lake. These shells are much worn, and may be regarded as being in 
a semi-fossil state. They are possibly shells Avhich lived in the lagoon when it was 
open to the sea. 
(2.) Shells found in great nnrabers on the shores of the lagoon. These are nearly 
all paired valves with their ligaments. They are all of a most definite type [mde 
MDCCCLXXXIX. — B. 2 S 
