XXXIV 
SYNOPSIS OF GENERA. 
Surface marked by concentric striae, which are often more or less lamellose. 
Interior unknown. 
The species referred to this genus were originally described as Sanguinolites. 
In the absence of a knowledge of their internal characters, they may be dis¬ 
tinguished from Sphenotus by their elongate sub-cylindrical form, widest at the 
posterior end ; want of defined umbonal ridge, with no fold on the post-cardinal 
slope. Sanguinolites , as illustrated and defined by McCoy, is synonymous in 
part with Allorisma, although the first species under the genus does not show 
this relationship. 
The two species of Spathella described, in external form and markings, seem 
to be related to the Lithophagi, but can be referred to no known genus. 
Examples: Spathella typica, pi. lxvi, figs. 36-40. 
Spathella ventricosa, pi. lxvi, figs. 41, 42. 
Conocardium,* Bronn (Lethaea Geognostica, vol. i, p. 92. 1835). 
[Type, Cardium Hibernicum, Sowerby.] 
Shell equivalve, inequilateral, more or less fusiform or trigonal. Posterior end 
obliquely truncate, produced along the cardinal line into a siplional tube and some¬ 
times the antero-inferior margin is also produced. Anterior end conicaland gaping 
in front. Beaks prominent and strongly incurved. Ventral margins crenulated. 
Cardinal line straight. Umbonal ridge prominent and ornamented with an 
expansion of the test in continuation of the truncated posterior end. 
Surface marked by concentric striae, and usually ornamented with strong radii. 
Hinge with anterior and posterior laminar teeth [Ba'rrande]. Ligament 
external. Muscular impressions two in each valve, situated near the cardinal 
extremities. Pallial line simple. In the anterior end there is a thickening or 
internal process forming apparently a foot-sheath. 
Examples: Conocardium cuneus, pi. lxvii, figs. 1-32; pi. lxviii, figs. 1, 4-16; 
pi. xciv, figs. 11, 12. 
Conocardium nor male, pi. lxviii, figs. 17-19. 
* Dr. Lindstrom, of Stockholm, writes that he has been engaged in the study of Conocardium, by cutting 
numerous specimens, and finds that they have no relation to the Cardiadre, a fact before suspected and 
believed by many persons, but never proved until the present time, 
