MY A. 113 



semble a lip. In this particular it bears some resem- 

 blance to the following species, which derives its trivial 

 name from the inequality of its valves. 



UNEQUAL-VALVED GAPER. 



40. Mya inaequivalvis. M. testa subtriangulari ; umbonibus incurvatis, 



gibbis. Linn. Trans. 8. p. 40. t. 1. f. 6. 

 Shell somewhat triangular; umbones convex and curved inwards. 

 Walker Test. Minut. Rar. pi. 3. f. 85. Encyclop. Method, pi. 230. f. 4. 



a. b. Mont. Test. Brit. p. 38. item. Suppl. pi. 26. f. 7. 



This is a small species, which seldom equals half an 

 inch in breadth. It is thick, rough, of a dirty white 

 colour, and has dissimilar valves, the upper one being 

 smaller and not so deep as the other. The lower valve 

 projects, on the fore part, into a beak, and is strongly 

 striated concentrically; the upper valve is marked also 

 in the same manner, and has besides a few distant 

 longitudinal striae. It is generally covered with a brown 

 epidermis. There is a strong triangular tooth in one 

 valve, which fits into a notch in the other. There are no 

 lateral teeth. 



Single valves of this shell are common on the Sand- 

 wich shore, but perfect shells are seldom obtained 

 unless dredged from the deep. Mr. Montagu noticed 

 it on the coasts of Cornwall and Devonshire, and pro- 

 cured live specimens in Salcomb Bay. 



Bruguiere has placed this shell in a new genus, under 

 the name of Corbula. 



VOL. I. 



