214 LUCINID A. 
grooved ; the ligament must have been thin, for there is only a 
short very narrow space immediately behind the beaks for its 
attachment, no special nymph being present. 
Differs from Unicardium in the number and position of the 
hinge-teeth. 
CorpicELLA, Morris and Lycett, 1853. 
EKiym.—Diminutive of Corbis. 
Distr.—Fossil, 7 sp. Upper part of Inferior Oolite— 
Oxfordian; England, France. CC. subsquilatera, Lycett 
(cxix, 60). 
Shell destitute of ornament, ovately elongated, rather com- 
pressed ; anterior side small; hinge characters differ from those 
of Corbis, in the absence of the anterior lateral tooth, and in the 
oblique internal ridge passing downwards behind the anterior 
muscular scar. 
Corbicella is intermediate between Corbis and Tancredia ; 
and from the latter, to which it is more nearly allied, it is sep- 
arated by its more ovate form, and by the absence of the 
posterior oblique angle, and in the possession of a lengthened 
hinge-lamina and depressed remote posterior lateral tooth. 
Morris and Lycett state the anterior lateral tooth is always 
wanting, but though not well developed, it is certainly indicated 
by the internally strongly thickened margin in such species as 
Corb. depressa, Desh., and still more in Corb. Barrensis, Buy. 
SporTELLA, Deshayes, 1852. 
Distr.—Fossil, 17 sp. Tertiary; Paris Basin. S. Cazlletz, 
Desh. (cxix, 61). 
Shell oblong, smooth, depressed, subequilateral ; valves closed. 
Hinge narrow, with two unequal, diverging teeth in the left 
valve, one in the other ; the lateral teeth are wanting. Muscular 
sears large, oval, nearly equal; pallial line simple. Ligament 
external. 
Possibly some of the Liassic species referred to Unicardium 
belong to this genus. 
SPHARELLA, Conrad, 1838. 
Distr.—3 recent sp. California, Guayaquil, N. Zealand. 
Cretaceous, Tertiary; United States, Europe. C. concentrica, 
Conr. (cxix, 63). 
Shell rounded, tumid, thin; hinge with two cardinal teeth in 
each valve, the posterior one in the right valve broad, bifid, par- 
allel to the hinge-margin, in the left single, but equally elongated. 
Some of the paleeozoic Lucinze may belong to this genus. Conrad 
and others class it near Diplodonta, but the prolonged posterior 
teeth appear to indicate a greater relation for the various Corbine. 
