314 
MR. W. BATESON ON SOME VARIATIONS OF CARDIUM EDULE 
Plate 26, tig. 11) being moderately thin shells, having generally the anterior 6 to 10 ribs 
yellowish-white in colour, and the posterior 7 to 12 bluish or chocolate coloured; the 
inside of the shells is much ribbed ; the posterior part is generally chocolate colour, and 
sometimes the whole interior of the shell is so coloured. Many of the shells have bands 
of dark colour running transversely to the ribs. The shells are nearly all elongated. 
The average ratio of length to breadth in 30 shells varying in length between 27 mm. 
and 20 mm. is 1 : 0’680 ; as in other samples, the elongation is more marked in large 
shells than in small ones. 
The beaks are rather variable, but in most shells they are low. 
The peculiarities in colour of these shells are so definite that they could not possibly 
be mistaken for the shells of Cockles from any other locality. 
Amongst these modern shells are a few of the old serai-fossil shells mentioned 
above, which, however, are so different from them, being bleached and worn, that 
they may be at once distinguished. 
Eamleh Lake No. 1. 
By the formation of the Mahmudiyeh Canal, which was begun in 1819, a small 
piece of water w^as separated from the great Lake Mareotis, in the neighbourhood of 
Sidi Caber station. 
This lake is about a mile in greatest diameter, and its wnter is at the present time 
fresh, receiving much waste water from the irrigations, and is, perha})S 10 to 12 feet 
deep in the middle, though shallow at the sides. The bottom at the sides is sand, 
and in the middle is mud. Great quantities of Cockle shells lie on the bottom of the 
lake, but I found no live animals, and believe that they are extinct. These shells have 
a definite character, being thick and coarse in texture, with 14 to 16 anterior ribs, 
white, and from 3 to 5 posterior ribs, chocolate colour. The region of the anterior 
ribs (6 to 10) is generally not ribbed on tbe inside of the shell. The insides of the shells 
have a peculiar wdiite colour. The shells are very long in proportion to them breadth, 
and most of them have one or more deeply marked lines of growth. The beaks are 
high and large. Amongst the smaller shells found here are some few which are 
extraordinarily thick. 
RamleJt Lakes Nos. 2 and 3. 
By the construction of the railway from Alexandria to Cairo, 1855, a second part of 
Mareotis has been cut off by an embankment, and the lake thus formed was again 
divided into two by the embankment recently made to connect the Cairo railway with 
the Ramleh line. In this way two lakes liave been formed, an eastern (No. 2) and a 
western (No. 3). Both of these are fresh, receiving the water from irrigations. In 
the western lake I found no Cockles af- all, either dead or living, though the water is 
crowded with Prawns {Palcemon, sp. ?). 
