48 
2. Depth of Voices. — The valves are invariably strongly convex, in 
some cases to a high degree. This reaches its utmost development in 
E. cordata, as figured hy Daua,^ and at a minimum in E. elliptica, Dana.^ 
Morris speaks of E. cordata as a “ very ventricose and cordiform shell. 
The width of the valves is also clearly shown in one of Sowerby’s figures, a 
typical internal cast of E. cordata, Morris.^ TTom the examination of a 
large series of specimens we find that the ventricosity or degree of convexity 
•Df the valves in E. cordatum is high, and in elevation the valves are much 
arched. This is most marked in the suh-umbonal region, thence the convexity 
rapidly decreases towards the ventral margins, where the valves are more or 
less compressed or ‘‘thin.” The large specimen (PI. XVII), already 
referred to, has a girth of fourteen and a half inches. E. hohartense, as 
compared Avith the typo species, is a compressed form, with a thickness, 
through the apposed valves, of four and a quarter inches. 
3. Valves. — The valves Avere closely apposed in both species, there 
being no gape. IVe are in accord with Dr. AVaagen in that the “gaping 
lunette ” referred to hy Stolickza does not exist.® 
The cardinal margins are sharply arched in both species, the angle of 
the anterior side being decidedly the more acute. The margins of the valves 
Avere closely ajjposed, leaving no dorsal or anterior gape as in Meleaqriiia. 
The portion which is regarded as the ventral margin is relatively of 
small extent, sharply and obliquely curved. This region is invariably regularly 
convex, or rounded, except in Dana’s E. sacculiis,^ Avhere the margin is 
insinuate immediately opposite to the umhonal region, corresponding to 
shalloAV cinctures. It must he pointed out that if Dana’s species he D achydomus 
sacculiis, McCoy, ~ it differs Avidely from McCoy’s figure, in that the latter 
shoAvs only the merest ventral inflection on the valve figured. The greatest 
degree of convexity is seen in Dana’s figure of E. cordata, Morris,® Avhere it 
forms almost a semicircle ; in E. elliptica, Dana,® the curvature is much 
wider. 
> V>ma.—Op.cit., PI. VIII., fig. la. 
‘ Dana — Op., cil., PI. A^II., fig.s. 6 b and c. 
* Morris in Strzelecki — Phys. Descr. N. S. VA'ales, p. 276. 
‘ Sowerby in Mitchell — Op. cit., PI. II , fig. 2. 
® Waagen — Salt Range Fossils, loc. cit., p. 13. 
* Dana in AVilkes — Op. cit., PI. VII, fig. 8a. 
' McCoy — Ann. Mag. Nat. Hist., 1S47, XX, PI. XIV., fig. 5. 
* Dana in AA^ilkes — Op. cit., PI. VIII, fig. 1. 
s Dana in AA'^ilkes — 0/». cit., PI. VII, figs. 6a, d. 
