CUCULL/EA. 



Lam. — Hist. Nat. des Anim. sans vert^ t. 6. p. 33. 



TESTA subaequivalvis, inaequilatera, trapezifor- 

 mis^ ventricosa ; umhonihus distantibus^ area 

 li^amenti separatis. Impressiones musculares 

 duae ; antica elevata^ margine angulato, vel in 

 auriciilam producto. Cardo linearis^ rectus^ 

 flentibiis minimis subtransversis instructus ; utra- 

 que extremitate costis duabus ad quinque^ sub- 

 parallelis. Lig amentum externum. 



That the Cucullcece resemble the Arcce very nearly in their 

 general external form, in the area which bears the liga- 

 ment, and in their straight linear hinge, we do not in the 

 least wish to deny ; but there are two particularities, be- 

 sides that of the hinge teeth, by which we think they may 

 be easily distinguished, and which renders it necessary to 

 separate them : the first is, that in Cucullaea the two 

 valves are not exactly alike ; and the other, that its animal 

 does not appear to attach itself to submarine bodies by a 

 bi/ssus, as that of the Arcae does. From this last circum- 

 stance in particular, we doubt the propriety of arranging 

 the Cucullcea with the Arcacea. One observation further 

 seems here necessary ; Lamarck says, that the singular ribs 

 ( cotes ) at each extremity of the hinge teeth, ought not to be 

 considered as teeth, but we think that they ought, as they 

 answer the same purpose as the lateral teeth in other 

 bivalves ; and, moreover, as they appear to be a continua- 

 tion of the hinge teeth, only gradually increasing in size 

 and changing their position. 



A subequivalve, inequilateral, trapeziform, very ven- 

 tricose, bivalve j the anterior portion is rendered distinct 



