BIVALVIA. 187 
Length, +ths of an inch: height, “ths ditto. 
Locality. Mam. Crag, Bridlington. Recent, Britain. 
One specimen only of this species has come under my observation, it was found by 
Mr. Leckenby, who has obligingly permitted me to have it figured. 
If it were in almost any other genus than the present, the differences between this 
shell and the figure and description given, above referred to, might, perhaps, be 
sufficient to justify its being considered a new species; but with only a single specimen, 
I am unwilling to do more than refer it to one already established. Our present shell 
may be further particularised as having a prominent and sharp umbo curving a little 
over a lunule, large and deep; the ridges upon the exterior are large, somewhat 
prominent and rounded, about as wide as the spaces between them, and on the anterior 
side they extend up to the lunule, and there stop rather abruptly ; while on the 
posterior side, in the young state, they reach to the edge of the corselet, becoming 
obsolete and nearly smooth down the slope in the older part of the shell ; our specimen 
is more equilateral, less broad posteriorly, and of a more triangular form than the 
figures above referred to, but in other respects there is so great a resemblance that 
it may be considered as probably an aberrant form of the above species. The 
lunule and corselet are smooth, or, at least, show only lines of growth, and the 
numerous and close set ridges seem to remove it from any specific connection with 
A. sulcata. 
A fossil in the Cabinet of Mr. Morris, brought from the mouth of the Varga, 200 
miles up the Dwina, by Sir Roderick Murchison, more resembles the figure and 
description of eredricostata in the ‘ Hist. of Brit. Mollusca.’ 
15. ASTARTE PYGM@A, Minster. Tab. XVII, fig. 7 a—b. 
ASTARTE PYGM@A. (Miinst.) ex Goldf. Pet. Germ., vol. ii, p. 195, t. 135, figs. 5, 6a, 5 
(excel. syn.) 
— — S. Wood. Catalogue, 1840. 
, 
Spec. Char. Testa minutd, orbiculato-trigond, compressiusculd, equilaterali, umbonibus 
prominulis ; concentricé costatd, costis crebris, convexis ; margine crenato vel tntegro. 
Shell small, roundedly trigonal, somewhat compressed, equilateral; umbones 
slightly prominent, concentrically costated; ridges thick, numerous, and convex: 
margin crenulated or smooth. 
Diameter, +th of an inch. 
Locality. Cor. Crag, Sutton. 
This species is exceedingly abundant at the above locality, but the valves are 
rarely found united. It appears to correspond with the figure and description by 
Goldfuss. 
Our shell has the posterior dorsal edge somewhat rounded, and the longitudinal 
diameter generally exceeds the height; the umbo is neither very sharp, nor very 
