364 MARSHALL: ADDITIONS TO “ BRITISH CONCHOLOGY.” 
The fry are roundish, becoming gradually oblique and then 
triangular. 
A. crenata was dredged between the Hebrides and Ferces by 
the ‘Triton,’ and I have a specimen taken from a haddock 
by Mr. Baillie of Brora. As Vicania crenata (Gray, 1824) 
it is prior to A. crebricostata (Forbes, 1847), and although 
considered two species by some authors, the differences 
are considered by others to be too slight to warrant their 
separation. 
Circe minima Mont.—Young shells closely resemble the 
same stage of Venus exoleta, but are flatter. ; 
Var. triangularis Mont.—Guernsey, 18 f. ; Loch Linnhe, 
40 f.; Loch Boisdale, 30 f., a valve. 
Venus.—The very young and fry of the Veneride are difficult 
to discriminate. Those of % exoleta, V. fasctata, and V. 
casina are almost identical from the fry up to a line in 
length, having each the same shape and being closely 
sculptured with fine concentric striz. In fact, all the 
species except V. ova¢a are finely striated at first, the 
characteristic sculpture of each not appearing until after- 
wards. In V. exoleta the fry are broader, coarser, and 
flatter than in V. “incta, but they are very much alike. 
Those of V. fasciata are quite unlike the adult; the strize 
are fine and close set, and they are scarcely separable from 
the same stage of V. gallina, but the striz of the latter are 
coarser. Those of V. casina and V. fascitata are alike in 
sculpture, but the latter are more sharply triangular in 
shape. And those of V. verrucosa are similar to V. casina, 
but the interstitial striz of the former will always distin- 
guish them. 
It may seem superfluous and hardly worth the trouble 
to study the immature forms of the mollusca. But some 
of them differ very much from the adult stage, and when 
investigating and classifying the results of dredgings it is 
J.C., vii., Apr. 1897. 
