CO^CRYLIA—DITHYRA. 7. 31 



Shell transverse, equivalve, open at the sides. Hinge with a single 

 elevated transversely dilated tooth in the left valve, and none in 

 the right : lateral teeth none Ligament internal. 



The shells of this genus are generally found buried in gravel or 

 hard clay, and are furnished with a long contractile and extensile 

 tube of suction at the anterior end. 



M?A testa oblongd convexd, latere antico truncato, dente rotunduto truncata. 



simplid. 

 Shell oblong convex, truncate at the anterior end, with the tooth 



rounded and simple. 

 Mya truncata Linn. Syst Nat p. 1112. 



Gmelin. Syst. p. 3217. 



Turton, Linn. Syst. iv. p. 174. 



Pennant, Brit. Zool. iv. p. 159, tab. 44. 



Chemnitz, vi. p. 8, tab- 1, fig. 1 and 2. 



Montagu, Test. Brit. p. 32. 



Donovan, Brit. Shells, iii. tab. 92. 



Linn. Trans, viii. p. 35. 



Turton, Brit. Fauna, p. 146. 



Dorset Catal. p. 27, tab. 3, fig. 1. 



Wood, Conch, p. 90, tab. 17, fig. 1 and 2. 



Dillwyn, Descript. Catal. p. 42. 



Turton, Conch. Diet. p. 97. 

 Chama truncata. Da Costa, Br. Conch, p. 233, tab. 16, fig. 1. 

 Chamse Pholas latus. Lister, Conch, tab. 428. fig. 269. 

 Mus. nost. Gravelly and muddy shores. 



