May be easily known from the Mactra and Lutraria, as the valves, when
closed, fit exactly, and do not gape. It is remarkable that all the
living species contained in this genus only exist in the seas of
Australasia, while at least seven species in a fossil state are found in
France.
Shell inequilateral, sub-orbicular, close, equivalve, sometimes
attenuated at one end; two divergent primary teeth, with a cavity at the
side; lateral teeth obsolete; ligament internal, inserted in the cavity
of the hinge.
Crassatella Kingicola.
C. donacina.
C. sulcata.
C. subradiata.
C. contraria.
C. cuneata.
C. rostrata.
C. glabrata.
C. erycinæa.
C. cycladea.
C. striata.
_C. sulcata._ The furrowed Crassatella. Pl. 6, fig 4.
Shell ordinarily thick, striated transversely, denticulated,
sub-triangular, equivalve, inequilateral, summits well marked and
evidently turned forward; hinge very large, subsimilar, formed by two
diverging cardinal teeth, separated by a large pit; ligament almost
entirely interior, and inserted in the pit.
_C. Kingicola._ The King’s Island Crassatella.
Ovate, orbicular; yellowish white, with obsolete rays; very minutely
striated transversely; the umbones somewhat plicated.