573 



fide,*^ on the margin of the cartilage flope, on both 

 valves, become confluent in pairs, and form fliort, ob- 

 tufe fpines, reflecting backwards ; this double row of 

 fpines forms a deep cavity for the cartilage : umbo fmall, 

 nearly central, and turned a little to one fide, beneath 

 which, is a ftrong, lanceolate, cordiform depreflion. 

 Infide fmooth, white ; hinge furniflied with a fingle pri- 

 mary tooth, and a fmall cavity on each fide in one valve, 

 which locks in between, and reciprocally receives two 

 in the other valve ; the former has alfo a remote, late- 

 ral Lamina on each fide, which the latter is deftitutc of, 

 or very obfolete : the margins are plain. Length half 

 an inch ; breadth rather more. 



This new, and interefting fpecies, has fomewhat the 

 habit of that rare, and valuable fliell Venus Dionc ; and, 

 indeed, is not unlike the figure of it given by Lister, 

 but the fpines are neither fo confpicuous, nor placed fo 

 remote from the end ; this fliell, too, wants the inner row 

 of fpines on each fide, obfervablf in the other, and alfo 

 differs fomewhat in the hinse. 



In fliape, it much refembles Venus flriatula, but rather 



longer in proportion to its breadth ; the concentric 



ridges are, however, finer ; and more refemble thofe on 



the young TcUina Radula. 



We 



* This is ufually termed tlic anterior end, but certainly is more properly 

 tlie pofterior, tor the tube, or part trom wiiich the animal receives fuftenancc, 

 is protruded at the other end ; and in all bivalve fliells, is tippermoft in their 

 native fand. 



