84 CARDIAD^. 



The ventnil margin is arcuated in the middle, ascending 

 more or less obliquely in front, and rising, although in a 

 lesser degree, at the posterior side likewise. The front 

 dorsal edge, in the younger examples, is very short, and 

 not at all sloping, and forms a very obtuse angle with the 

 but slightly convex anterior margin, which latter, as age 

 advances, curves outward, when the angulation becomes no 

 longer perceptible, and the front outline appears to form 

 one uninterrupted sweep from the umbones to the ventral 

 margin. The hinder dorsal edge is almost straight, 

 almost equally devoid of declination, and forms at its ter- 

 mination a more or less rounded off angle with the curved 

 posterior edge. The lower corner of the hinder side, which 

 is very greatly the superior in length, is likewise rounded. 

 The umbones are prominent ; the beaks are acute, inflect- 

 ed, and lean a little towards the small and narrow im- 

 pressed lunule ; the ligament is small, and not at all pro- 

 jecting. The hinder dorsal area scarcely presents a trace 

 of that flattening of surface so habitual in the genus ; the 

 umbonal ridge is consequently well rounded, and not 

 strikingly manifested. The internal surface is of a pure 

 unstained white, often shining with a slightly pearly lustre ; 

 the front lateral teeth are the more approximate. The length 

 is almost one-third of an inch, and the breadth is very 

 slightly inferior. The animal appears to be entirely white. 

 It is not alone the rarest of our Cockles, but one of 

 our scarcer British shells, having been hitherto met 

 with in scanty numbers, and out of Britain only in the 

 Norwegian seas. The first recorded specimens are stated 

 by Mr. Thompson to have been extracted from the sto- 

 machs of some common soles {Solea vulgaris), which had 

 been caught off the eastern coast of Ireland, and exposed 

 for sale in the Dublin market (Dr. Farren). Subsequently, 



