1^4 ^^' William Wood's Ohfa-vatlons on the 



■■^- . ' Tab. XVI. Fig. 3, 4. 



The valves of this fliell are firmly connected together, 

 by a quantity of cartilage feated in two fpoon-ihaped 

 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 th& 

 whole is received between two teeth in the oppo- 

 fitc valve. 



Da Cofta, when he wrote his Brltifo Conchology, was 

 not aware that this fhell formed a diftindl fpecies 

 from the following ; he has therefore dcfcribed and 

 figured the M. hians a under the name of Chctma 

 magna^i while his Synonyms dire6l the reader to the 

 M. hit r aria, 



hians. Da Cojl. Br, Conch, p, 231. /. i*], f,\. 



Tab. XVI. Fig. 5, 6. 



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

 more fpread, but not fo regularly fliaj^ed as in the 

 preceding. The great tooth in the upper valve locks, 

 like that in the M, luiraria, between two teeth in 

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

 fpecimcn before me, is grooved longitudinally, and, 

 when the fhell is clofed, fits into a fmall cavity on 

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

 likewife be noted, that theie is in both valves a 

 deep, narrow fulcus, which runs from the beak of 

 the fhell acrofs the bale of the great cavity, and clofe 

 on the infide of the teeth. 



Jiultorum, 



