366 MARSHALL: ADDITIONS TO ‘ BRITISH CONCHOLOGY.” 
1}? inches by r# inches ; these are flatter than usual, and 
have the same outline as Zapes aureus. 
Var. laminosa Mont.—Torbay ; Pendine; Doggerbank, 
20 f.; Aberdeenshire, 30 f. In this variety the ribs are : 
sharper and fewer. The young, as well as those of the 
var. gibba, differ from the same stage of the type at a very 
early age, and may be separated without difficulty. 
Var. triangularis Jeff.—Dorsal margin longer, straighter, 
and more angular at the base; the shell is also longer 
in proportion to its breadth. Brora (Baillie) ! ; Weymouth ; 
Menai Straits ; Oban. 
Var. gibba Jeff-—The author says of this variety, “ribs 
numerous and irregular,” but his figure shows the ribs 
much less numerous than his type figure, and this character 
is in fact variable in all the varieties. ‘The shape of his 
figure is right, and that is its only permanent character ; 
the “ribs confluent or bifurcating on the posterior side” 
being common to all the forms of this species. The very 
young are smooth and glossy, the ribs forming at a later 
stage than in the other varieties. This is zo¢ the Mediter- 
ranean form ; the latter has the same triangular outline, but 
is not gibbous. The Crag form appears to be similar to 
the Mediterranean one. 
Var. alba Somerv. — Shell milk-white. St. Bride’s Bay. 
There is also a colourless form of a dirty white. 
Venus mesodesma of Quoy and Gaimard was _ intro- 
duced into Little Ferry, N.B., from North America, by the 
late Duke of Sutherland in 1885 ; but they soon perished, 
and the empty shells only are left. A half-grown living one 
was sent me in 1890 by Mr. William Baillie, which was 
probably the last. It is a large and handsome species. 
‘VW. mercenaria L.—A fine series has been dredged alive 
in the river Humber. It was first observed in 1864, and 
again in 1868; it has steadily increased to the present 
J.C., viii., Apr. 1897. 
