DESCRIPTION. 147 



Shell compressed_,flat^ suborbicular; hinge trans- 

 verse, imbricate^ having thelaminae toothed in rays. 



Lister Conch, tab. 223. fig. 57. 



Specimen whitish with crimson rays^ within 

 pearly ; being young it does not possess the tooth- 

 like scales which are found in older shells. Hinge 

 very straight, the length of the whole shell. 



Inhabits the American Ocean. 



A distinct variety, differing in size and in other re- 

 spects from the East Indian Pearl-bearing muscle. 



Fig. 5. M. edulis. 



Shell smooth, violet ; valves rather carinate be- 

 fore, retuse behind, beaks pointed. 



Lister Conch, tab. 362. fig. 200. 



Specimen deep violet, beaks white ; somewhat 

 triangular. 



Inhabits most seas, at the bottom of which it is 

 found adhering by the byssus in large clusters. It 

 is generally known as the common muscle. 



PLATE XL 



Fig, 1, Pinna pectinata. 

 l2 



