40 INVERTEBRATA OF MASSACHUSETTS. 



accordingly, it is not difficult to obtain specimens through the fishermen. 

 In young shells the epidermis is smooth, and of a light chestnut- 

 color. 



Family MYARIA. 



Shell often inequivalve, inequilateral, gaping ; hinge with an erect, more or 

 less spoon-shaped tooth in one valve, received into a corresponding excavation 

 in tlu opposite valve, united by an interposed cartilage. 



Genus MYA, Lin. 



Shell transverse^ gaping at both ends ; left valve ivith a single 

 broad, compressed, erect tooth, received into a pit in the opposite 

 valve. 



Mya arena'ria. 



Shell transversely ovate, chalky-white, covered ivith a thin, 

 wrinkled epidermis ; tooth of equal length and breadth, inclined 

 a little backwards and inwards, ivith an oblique rib on the back. 



State Coll., No. 234. Soc. Cab., No. 1722. 



Mya arenaria, Lin.; Syst. Nat., 1112. Pennant; Brit. Zool., iv. 7'J, t. 42, 

 f. IG. Chemn ; Conch., vi. 10, t. 1, f. 3, 4. Fabr. ; Fauna Grant., 40&. 

 Dillwyn; Cntal., I. 42. Bruu., Encyc. Meth., pi. 229, f. 1 to 8. Blainv. j 

 Malacol. \)\.17 , f. 1. Sovverisy ; Gcyjcra, No. 32. Montagu; Test. Brit., 30. 

 Wood; 6'en. Conch., 91, t. 17, f. 3. Index, -pi. 2, f. 2. Deshates ; Encyc. 

 M6th., Fers, ii. 592, pi. 229, f.l. Lam.; £n. sans Vert. {Desh. ed.), vi. 74. 

 Maton and Rackett; Lin. Trans., viii. 35. Turton ; Co7ich. Diet., 98. BriL 

 Biv.,52. Donovan; Brit. Shells, t. 85. Fleming; Brit. Jinim. 4G3. Con- 

 rad ; Jimer. Mar. Conch., 42, pi. 9, f. 1. 



Mya inercenaria, SSay ; Journ. Acad. jXat. Sc, ii. 313. 



Mya acuta, Say ; Jbid. 



Shell ovate, eqiiivalve, nearly equilateral, moderately thick, 

 gaping at both ends, especially at the posterior, which cannot be 

 closed on account of an outward curvature of the valves ; an- 

 teriorly shortest and regularly rounded ; posteriorly narrowed and 

 rounded ; surface wrinkled, and in some parts raised into ridges 

 at the lines of growth ; faint radiating lines and colors depart 

 from the beaks ; color dingy-white, covered with a very thin, 

 dirty-brown epidermis, irregularly wrinkled ; beaks small, pointed, 



