CONCHIFERA. 741 



Cardium isocardia L., HUMPH. Amb. Rariteitk. Tab. 48, fig. 9, CHEMN. 

 Conchyl. Tab. 17, figs. 174 176, &c. 



Hemicardium KLEIN, SPENGLER, Guv. Valves compressed, a keel 

 dividing the anterior from the posterior plane. 



Sp. Cardium hemicardium L., HUMPH. Amb. Rariteitk. Tab. 44, fig. H, 

 BLAINV. Malac. PI. 70 bis, fig. 4 ; Cardium cardissa L., LAM., HUMPH. 

 1. 1. Tab. 42, fig. E, &c. 



Of the genus Cardium SPENGLER has given a monograph, Skrivter af 

 naturhist. Selskabet, V. T. 1799, pp. I 60, Tab. I. 



The fossil species of Cardium are uncommonly numerous, they occur 

 especially in tertiary formations. 



Isocardia LAM. Shell cordate, with points involute spirally. 

 Two cardinal teeth under the points, compressed, entering ; a single 

 lateral tooth posterior, elongate. Animal (Glossus POLI) with foot 

 compressed and tentacles of mouth elongate, acuminate. 



Sp. Isocardia cor, Chama Cor L., BLAINV. Malac. PI. 69, fig. 2, POLI 

 Testae, utr. Sic. n. Tab. xxm. figs, i, 2 (i. Tab. XV. figs. 3436 animal) ; 

 Mediterranean, &c. ; also fossil. Much more numerous are the extinct 

 species of this form, which for the most part occur in secondary formations. 



Opis DEFRANCE. Fossil genus. Is this its place ? 



Comp. DESHAYES in LAMARCK Hist. n. d. Ani. s. v. vi. pp. 519, 520. 



Cypricardia LAM. Shell inequilateral, elongate posteriorly, 

 oblique or transverse. Three teeth under the points ; lateral tooth 

 single, posterior, compressed, acute. 



Sp. Cypricardia oblonga DESH., Chama oblonga L., Cypric. guinaica LAM., 

 BLAINV. Malac. PL 65 bis, fig. 6, DESHAYES Conchyliol. PI. 24, figs. 8, 9, 

 &c. ; Here belong also petrified species from the oolite and chalk 

 formations. 



Family XIII. Veneracea. Mantle with lobes fimbriated at 

 the margin, concrete posteriorly, open anteriorly for the passage of 

 large, compressed, acute foot ; two tracheae moderate, often coalesced 

 at the base. Ligament external, short. Shell equivalve, free, 

 regular, shut. Mostly three cardinal teeth, diverging obliquely 

 from the point; lateral tooth in some single, posterior, in most 

 none. 



Astarte SOWERBY, Crassina LAM. Cardinal teeth two, diver- 

 gent. Impression of mantle simple. Shell transversely rugose or 



