204 MOLLUSCA FROM THE CRAG. 
when the specimens can be compared; there are, however, some differences in the 
descriptions: it is therefore thought best to retain its present name. As this latter 
species appears its nearest relative, it may be only necessary to point out what are the 
distinctions, relying upon the description by that author, who, in comparing his shell 
with the geographica, seems to think a specific character exists in being less equilateral, 
and in the straight dorsal line of zfens, with a more convex ventral margin. Our 
shell, on the contrary, appears to have its dorsal margin more rounded than that of 
geographica, and much resembles in outline the viryinea, but the smooth and glossy 
exterior differs from all that I have seen, with the exception of xzfens; the dental 
characters appear the same, the central one bifid in the left valve, with two sub-bifid 
in the right; but the palleal scar, according to the figure, goes deeper into his shell 
than it does into our Crag fossil. 
4. Tapes TEXTURATA? Lamarck. Tab. XX, fig. 3a—c. 
Venus Texturata. Lam. Hist. des An. sans Vert., 2d ed., p. 355, No. 43. 
Tapes TEXTURATA. G, Sowerby. Thesaur. Conch. Tapes, No. 39. 
Spec. Char. Testa tenui, cordato-ovatd, compressiusculd, inequilaterah ; transversim 
striata, striis numerosis, confertis. 
Shell thin, ovately heartshaped, somewhat compressed, inequilateral ; transversely 
striated, striz numerous, close set. 
Length, 1 ich. 
Locality. Red Crag, Walton-on-the Naze. 
The specimen figured is the right valve with three teeth tyscns from imme- 
diately beneath the umbo. The lines which cover the exterior are generally parallel 
to the margin of the shell, but they occasionally anastomose, or run into each other 
like those upon the recent species, 7. ¢erturata. There is, however, a slight difference 
in form from that shell, and thelunule is not so distinctly marked; but having only one 
specimen, and that imperfect, I am unwilling to ao more than assign it provisionally to 
what appears at least its nearest relative; should, however, future examination of 
better specimens justify a specific distinction, I would claim for the Crag fossil the 
name of habilis. 
VENERUuPIS.* Lamarck, 1818. 
Venus (sp.) Linn. 
Donax (sp.) Id. 
Cuneus (sp.) Dacosta. 
Irus. Oken, 1815. 
Purricota (sp.) Turt., 1822. 
Pretrirora. Latr., 1827. 
Venerinuris. Blainv., 1825, G. Sow., 1839. 
Venervures. Swains., 1840. 
* Etym., Venus, and rupis, a rock. 
