CONCHACEA. 



MOLLUSCA. VENUS. 85 



and it has also been taken with the dredge by Drs. Mighels and 

 Wood of Portland, in the harbour of that place. 



Mr. Say knew it only as a fossil, in which state it occurs in the 

 tertiary formation of Maryland. 



This is by no means an attractive shell, its dead-white surface lead- 

 ing one to suppose it to be some beach-worn specimen of Cyprtna, or 

 perhaps of Verms mercendria. It is, however, much longer than the 

 former, and somewhat longer than the latter ; and it never attains to 

 any thing like the size of either of them. 



Genus VENUS, Lin. 



Shell inequilateral, sub-ovate ; hinge with three diverging car- 

 dinal teeth in each valve ; palleal impression with a sinus. 



Venus mercenaria. 



Shell solid, obliquely ovate, very inequilateral ; lunule heart- 

 shaped ; surface antiquated, bluish-white, with numerous, concen- 

 tric, laminated ridges ; inner margin broadly edged with violet. 



Figure ^.t". 



State Coll., No. 197. Soc. Cab., No. 1859. 



Venus mercenaria, Lin.; Syst. JVat., 113L Gmelin ; Syst., 3231. Lister; 

 Conch., t. 271, f. 107. Chemn. ; Conch., x. t. 171, f. 1659, 1660. Deshayes ; 

 Encijc. Mkh., Vers., iii. 117, pi. 263. Lam.; ./3w. sans Vert., vi. 346, pi. 263, 

 f. 1 to 3. DiLLWYN ; Catal., i. 176. Wood ; Index, pi. 7, f. 40. 



Shell large, thick and solid, obhquely ovate, or heart-shaped, 

 tumid ; exterior a dirty-white and chalky ; the beaks are placed 

 far forwards, projecting nearly to the front of the shell ; they are 

 elevated, and curved so as to make nearly half a turn forwards 

 and inwards ; in front of them is a heart-shaped, rough lunule, 

 bounded by an impressed line ; behind the beaks the edge is very 

 broad and obtuse, the ligament large and protuberant, with a space 

 around it somewhat excavated, smoother than the rest, and bound- 

 ed by an obtuse ridge ; anterior end very short, round ; posterior 

 end terminating in a blunt, occasionally truncated point ; looking 

 at the side of the shell as it stands on this point, it is accurately 

 heart-shaped ; surface with concentric grooves and ridges, the 



