164 Mr. William Woop's Ohfervathns on the 



Tab. XVI. Fig. 3, 4. 



The valves of this (hell are firmly conneded together, 

 by a quantity of cartilage feated in two fpnon-fliaped 

 cavities. On the fide of one of the cavities, in the 

 upper valve, there is a very ftrong tooth, the two 

 plates of which form an obtufe angle, and the 

 whole is received between two teeth in the oppo- 

 fite valve. 



Da Cofta, when he wrote his Britijlj Conchology, was 

 not aware that this iliell formed a diftinft fpecies 

 from the following ; he has therefore defcribed and 

 figured the M. hians a. under the name of Chama 

 magna, while his Synonyms dire(St the reader to the 

 M. lutraria, 



hians. Da Cojl. Br. Conch, p. 231. /. 17.^4. 



Tab. XVI. Fig. 5, 6. 



The great cavity in the hinge of this fpecies is larger, 

 more fpread, but not fo regularly fhaped as in the 

 preceding. The great tooth in the upper valve locks, 

 like that in the M. lutraria, between two teeth in 

 the lower valve, of which the outer one, in the 

 fpecimen before me, is grooved longitudinally, and, 

 when the (hell is clofed, fits into a fmall cavity on 

 the outfide of the tooth in the upper valve. It fliould 

 likewile be noted, that there is in both valves a 

 deep, narrow fulcus, which runs from the beak of 

 the Ihell acrofs the bafe of the great cavity, and clofe 

 on the infide of the teeth. 



Jiultorutn. 



