AVICULA echinata. 
TAB, CCXLIIL 
Syn. A. echinata. Smith’s Strat . Syst . p. 67, Strata 
Ident. p . 26, Cornbrash plate , f. 8. 
Spec. Char. Obovate, gibbose ; many muricated 
radii upon the deepest valve ; flatter valve 
smooth, with the anterior ear pointed. 
JP he deeper valve is a trifle longer than wide, with une- 
qual ears, the anterior of which is nearly right angled. 
The other valve is often wider than long, because the 
beak of it is not so prominent as in the convex valve : 
its anterior ear is elongated and pointed ; it is convex : 
in general it is smooth and free from radii, but in the one 
figured, which exceeds the usual size, it is radiated 
towards the margin. 
An abundant species in the Cornbrash Limestone, 
where it occurs in thin beds that contain great numbers 
closely pressed together, as is shewn in a mass I have 
from Chippenham, Wilts. Loose shells are found at 
Langton Herrn, near Weymouth, as I learn from Prof. 
Buckland’s specimens. 
The shells figured at No. 1 are from Pavingham, pre- 
sented to me by T. O. Marsh, Esq. 
Figures 2, 2 are from casts in a compact Limestone 
like the Lyas, but I do not know the locality* 
