84 

 CHAPTER XIX. 



OF THE MYTILUS. GENUS XVI. 



MYTILUS. 



"Animal an Ascidia ? Shell bivalve, rough, often affixed by a byssus ; hinge 

 without teeth, distinguished by a subulate excavated longitudinal line." — 

 Linn. 



LinnjEUs makes three divisions of this genus. The first he calls 

 " parasitical, affixed by claws." It contains only three species ; 

 the hinge in these is similar to that of the common Oyster, 

 with which they agree in most other respects, except that the 

 common Oysters are generally attached to rocks, stones, or 

 other substances, and these affix themselves by claws to twigs, 

 sticks, &c. ; they have also but one muscular impression. 

 Therefore it appears to be more proper to place these three, 

 viz, Hyotis, Frons, and Crista galli in the genus Ostrea, as 

 some authors have done. 



The second division Linnaeus calls " flat or compressed, ap- 

 pearing as if flat and somewhat eared." This consists of only 

 two species, M. margaritiferus and Unguis. The hinges of 

 both these differ from the genus Mytilus, arid from that of 

 Ostrea. If the animal is considered, it would lead one to place 

 them near to Ostrea Malleus, as it has only one mviscle, like 

 the Oyster, and fixes itself by a byssus, like Ostrea Malleus. 



