410 VENERID^. 



controversy, whether that species is specifically distinct 

 from the one so designated by the British writers ; we 

 snbjoin, therefore, a brief digest of the more striking 

 points of difference. The valves of gallina are always 

 more or less inflated, or at least ventricose, and their sur- 

 face covered with distant subimbricated grooves, which are 

 so peculiarly irregular as scarcely to be concentric (cha- 

 racters even more fully evident in the young than in the 

 old), their ventral margin is very strongly arcuated, and 

 their front dorsal edge short and much incurved; internally 

 the hinder extremity, or the muscular scar, is almost in- 

 variably stained with purple ; the crenations are coarse, 

 and not particularly numerous, and the sinus of the pallia! 

 impression is remarkably short. In sfriatula, on the con- 

 trary, the valves, whose shape is much more trigonal, are 

 frequently compressed, and very rarely are even ventri- 

 cose ; the surface, especially upon the umbones and in the 

 younger shells, is girt with distinct costella, which are by 

 no means peculiarly irregular, and, if distant, change into 

 lamella ; the arcuation of the lower edge is not remark- 

 able ; the front dorsal margin is long, and not strongly in- 



striffi ; but in the only large specimen we have had an opportunitj' of examining, 

 scarcelj' any such markings were observed but where the old shell had been super- 

 ficiallj' separated : the umbo is pointed and much reclined to one side, beneath 

 which is a broad cordiform depression ; but neither this nor the cartilage slope 

 differs in colour from the rest of the shell, which is wholly of a dirty-white. In- 

 side white : hinge furnished with four teeth in each valve, but the outer one 

 above the cordiform depression in one valve is obsolete, or formed only by a 

 cavity for the reception of the corresponding tooth in the opposite valve : the mar- 

 gin is finely crenulated. Length (breadth) more than an inch ; breadth (length) 

 above an inch and a quarter. 



The above description is taken from a shell in the cabinet of Mr. Laskey, 

 who assured us he took it by dredging off the Isle of May, in the Frith of Forth, 

 in the year 1804. In our cabinet is a single valve of about half the size of that 

 before described, which was found in Devonshire ; in this the longitudinal 

 strite are evident by the assistance of a lens, in the sulci between the tranverse 

 ridges." 



