I 



MYA. . 



TESTA transversa, iitrinqoe hians, dente cardi- 

 nali, in valva altera, unico, magno, compresso, 

 diiatato; valva altera eden tula ; impressionibus 

 muscularibus, diiabus, iateralibus, distantibiis, 

 antiea angustiore, postica siiborbiculari. /m- 

 pressiones musculares pallii sinu magno. Liga- 

 mentum internum, magnum, denti prominulo 

 in valva altera et in altera foveae affixum. 



A Gknus of marine shells, of which very few species 

 appear to exist, all belonging, as far as we know, to the 

 northern hemisphere. Those species which are at present 

 included in Mya form a very natural Genus, well charac- 

 terized by the large and prominent spoon-shaped process 

 to which the internal cartilage is affixed in one valve. 



It will scarcely now be necessary to point out the im- 

 propriety of continuing to unite together the Uniones, the 

 Corbuloe, the PanopcBce, the Anatince and the Glycimerides, 

 with our present Genus : the association is so evidently 

 unnatural, that, having already pointed out the reasons 

 for separating some of them, we shall here merely state 

 that they are now all separated by common consent, al- 

 though formerly confounded together in the Linn can Mya. 

 True Myae in a fossil state are, we believe, only found in 

 the Crag and its contemporaneous formations, though we 

 are aware that several have been described as fossil Myae 

 which belong to older beds; these indeed resemble them 

 closely in eitternal form, but can only be determined with 

 precision by the characters of the inside. 



The Myae appear to be most nearly related to the 

 Anatince and the Corbulce, and may perhaps be connected 

 with the Solenacece on one side, by the intervention of Pa- 

 nopcea, and with the Mactracece on the other by means of 

 Lutraria. The animal of the Myae lives buried in the 

 sand ; its epidermis not only covers the shell, but also 



