CARDIUM. 33 



less species, solely constituted from a bad figure (84) in 

 Walker's " Testacea Minuta Rariora," which bears about 

 equal resemblance to the young of Cardlum nodosum. 



0. suEcicuM, Reeve. 



Small, thin, suborbicular, very inequilateral, both within and 

 without of an uniform shining pure porcelain white ; ribs 

 about thirty, all armed with minute vaulted scales : ventral edge 

 much arcuated ; lower corners rounded- 

 Plate XXXII. fig. 6. 



Carduim Suediense, Reeve (March. 184.5), Conchol. Icoiiica, Cardium, pi. 22, f. 

 132, 

 „ Loveni, Thompson (May, 1845), Annals of Nat. Hist. vol. xv. p. 31 7, 



pi. IP, f. 7. 

 „ Suecicum, Loven, Index Mollusc. Skandinavise, p. 30. 



The shape of this rare and exquisite addition to our 

 Fauna, which was first described as an Irish production, in 

 the fifteenth volume of the " Annals of Natural History," 

 by Mr. Thompson (whose appreciation of its newness to 

 science was only anticipated by two months), is somewhat 

 obliquely suborbicular, the length, in the younger speci- 

 mens especially, somewhat exceeding the breadth. The 

 valves are very inequilateral, thin, and delicate, but opaque, 

 and of a pure and uniform lustrous porcelain white. Their 

 convexity is not considerable, but tolerably evenly diffused, 

 a little above the central disk being the most ventricose 

 portion of the shell. The surface is shining, and radiated 

 with about thirty rounded and not greatly-elevated ribs, 

 all of which are armed in the middle with very small and 

 crowded vaulted scales, and are separated from each other 

 by mere linear interstices, which become rather narrower 

 near the hinder extremity, and towards the beak aj)pear, 

 under a powerful magnifier, to be minutely punctated. 



VOL. II. F 



