SOLENACEA. MOLLUSCA. GLYCYMERIS. 39 



It is an interesting shell on account of the genus being found plenti- 

 fully on both continents in a fossil state, while recent specimens are 

 so rare. 



Genus GLYCYMERIS, Lam. 



Shell transverse, inequilateral., greatly gftping above and below ; 

 hinge margin callous, without a tooth ; ligament external, epider- 

 mis thick, extending beyond the margin of the shell. 



Glycy'meris siliqua. 



Shell transversely oval; epidermis black, dense, and shining, ob- 

 liquely wrinkled ; beaks eroded ; interior loaded with thick callus. 



State Coll., No. 235. Soc. Cab., No. 1721. 



Mya siliqua, Chemn. ; Conch., xi. 192, pi. 198, f. 1934. Dillwyn ; CataL, i. 49. 



Glycy'meris incrassata. Lam. ; Syst. des Jin. sans Vert., 126. 



Glycy'meris siliqua, Lam. ; .^ra. sans Vert., vi. 09. Blainv. ; Malacol.,^\. 80, f. 3. 

 AuDouiN ; Ann. des Sc. J\~at., 1833, pi. 14, 15, 16, (excellent.) Sowerby; Gen- 

 era, No. 8. 



Mya picea. Wood ; Gen. Conch., 96, pi. 22; f. 5. Index, pi. 2, f. 10. 



Shell oval, ponderous, widely gaping, surface undulated at the 

 different stages of growth ; covered with a thick, horny, glossy- 

 black epidermis, which projects a considerable distance beyond 

 the limit of the valves ; it is obliquely wrinkled at various parts, 

 especially at the posterior end ; beaks not prominent, always more 

 or less eroded ; ligament large and protuberant ; interior of the 

 shell white, loaded with a very thick mass of calcareous substance, 

 giving the shell great weight, its margin having a somewhat fringed 

 arrangement. Length Ig inch, breadth 3| inches. 



Its proper habitat is the Banks of Newfoundland ; but several 

 fine specimens have been hooked up or dredged in the neighbour- 

 hood of Provincetown, within Cape Cod. 



It is a very interesting shell, the only one of the genus yet known. 

 Its wide gaping, thick interior deposit, toothless hinge, and black ex- 

 terior, render it impossible to confound it with any other shell. The 

 great size of the animal, which the shell can never enclose, renders it 

 a welcome morsel for that denizen of the Banks, the cod-fish ; and, 



