BIVALVIA. 133 
some of the smoother specimens of anceps make great approaches to it. Both cordcs and 
anceps are very abundant in the Coralline Crag. 
Carpiva sEntiis, Zam. Crag Moll., vol. ui, p. 165, Tab. XV, fig. 1 a—/. 
Localities. Cor. Crag passim. Red Crag passim except Walton Naze. 
The shell which has hitherto gone by the name of Cardita senilis, Lam., is one of the most 
abundant shells in the Coralline Crag, and it is found also in all parts of the Red Crag save 
Walton, in some, if indeed not all, of which, however, it is probably only present as a deriva- 
tive. ‘There is some doubt whether this shell be the Venericardia senilis of Lam. or the 
Cardita rudista of the same author, under which latter name it is figured by Hornes, Tab. 
XXXVI, fig. 2, a—d, who associates with it (and I think justly) Chama rhomboidea, 
Broc., Tab. XII, fig. 16. In ‘Brit. Conch.,’ vol. i, p. xcil, Mr. Jeffreys says, “The Cardita 
senilis of the same beds (Coralline Crag) is the C. swlcata of the Mediterranean,’ and 
this he has repeated in the list annexed to Mr. Prestwich’s Cor. Crag paper. I have, 
however, carefully compared swcata with the Crag fossil and I cannot coincide in Mr. 
Jeffreys’ opinion. The recent swcata has more rounded ribs, which are nearly smooth, 
and not imbricated, and the ribs are united at their bases, but in seis they are distant, 
with a space between them. Seni/is is exceedingly variable in form, as may be seen by 
the specimens figured in ‘Crag Moll.,’ vol. i, Tab. XV, fig. 1 a—/, all of which I 
believe belong to one and the same species. As so many British authors have referred 
to this shell for nearly half a century under the name sezzlis, I have not thought it 
desirable, notwithstanding Dr. Hérnes’ identification of it with Lamarck’s rudista, to make 
any change in the name. 
Carpium Fasciatum, Mont. Crag Moll., vol. ii, p. 153, Tab. XIII, fiz, 4 (as C. 
nodosum). 
Localities. Cor. Crag passim. Red Crag passim. Chillesford bed, Aldeby. 
The shell figured in ‘ Crag Moll.,’ under the specific name of xodoswm may probably 
be C. fasciatum, Mont. (C. elongatum, Turt.), as has been said by the author of the 
‘Brit. Conch.’ Although a very common shell in the Cor. Crag, the specimens have 
(with very rare exceptions) the entire surface removed, and with it the tubercular orna- 
ment, and in that state it is of very difficult determination. Mr. Crowfoot sent me 
several small specimens from Aldeby in which parts of the exterior ornament is well 
preserved, and these may be referred to this species. 
