xxxiv SYNOPSIS OF GENERA. 



Surfivce 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. Ixvi, figs. 36-40. 



Spathella ventricosa, pi. Ixvi, 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 siphonal 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 [Barrande]. 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. Ixvii, figs. 1-32; pi. Ixviii, figs. 1, 4-16; 

 pi. xciv, figs. 11, 12. 

 Conocardium normale, pi. ixviii, figs. 17-19. 



• Dr. LinilHti orii. of Stookhnlin, writes that he has been eiigag'ed in thi! stndy of Omocardiiim, by cutting 

 numerouR 8|>ecimen8. and finds that they have no i-elation to the CardiaUie, a fact before suspected and 

 believed by many persons, but never proved until the present time. 



