MYTILUS. 305 



Britain. Lister, 8[c. Norway, Iceland, Greenland, and the 

 Ferroe Islands. Midler. 

 Shell an inch or an inch and a quarter long, and about half as 

 broad ; of a dirty white colour, covered with a yellowish 

 epidermis, and very rugged concentric wrinkles; it varies 

 much in shape, some shells being much broader and more 

 cylindrical than others, and this variation may probably have 

 misled Linnaeus to describe the species under two different 

 names. 



coralliophagus. 11. Shell carinated in the mid- 

 dle, with the margin crenated, and the urn- 

 bones obtuse. 



Mytilus coralliophagus. Chemnitz, viii. p. 174. t. 84. f. 

 752. Gmelin, p. 3359. 



Mytilus, No. 15. Sckroeter Einl. iii. p. 457- 



Mytilus. Enc. Method, t. 219. f. 4. 

 Inhabits the East and West Indian Seas, and perforates rocks 



and coral like a Pholas. Chemnitz. 

 Shell about three quarters of an inch long, and less than half as 



broad at the broadest part, which is towards the hinge ; the 



colour is whitish. 



pRvECisus. 12. Shell oblong, distorted, with the 

 valves unequal, and strongly wrinkled trans- 

 versely ; hinge terminal. 



Mytilus praecisus. Montagu Test. p. 165. t. 4. f. 2. Ma- 

 ton and Racket, in Lin. Trans, viii. p. 112. 



Inhabits the Western coasts of England and Wales, adhering to 

 the roots of Algae, or burrowed in lime-stone. Montagu. 



Mr. Montagu has given the following description of this spe- 

 cies, " Shell oblong, irregular, rugose, wrinkled, and fre- 

 quently much distorted ; commonly so much the shape of 

 the Solen minutus, as to be easily confounded for a worn 

 shell of that species, having lost the spines ; others resemble 

 the Mytilus rugosus. The particular characters are that the 

 hinge is close to one end, which side is quite square as if cut 

 off; the beak, large, prominent, and projects further in one 

 valve than the other ; which valve is rather largest, and re- 

 ceives the other within its margin, particularly at the oppo- 

 site end from the hinge. In some both ends are truncated ; 

 colour dirty white, frequently covered with a brown epider- 

 mis. Inside white, hinge rough, strong, inflected, forming 

 a deep cavity underneath the margin. Length from hinge to 



vol. i. x 



