108 MYA. 



land, Sweden, Norway, Saxony, and England. Mr. 

 Montagu mentions it as common in the rivers of De- 

 vonshire which take their rise from the mountains of 

 Dartmoor, and adds that it is not uncommon in the 

 northern parts and in Wales. 



It is this shell which occasionally produces pearls, 

 as has been already observed, in the general observa- 

 tions to the genus Mya. The shell represented in the 

 upper figure of pi. 23, has been selected for the purpose 

 of showing the usual situation of the pearls in these 

 shells, though they are sometimes found more towards 

 the centre. 



WRINKLED GAPER. 

 PL 24. /. 1, 2, 3. Mrs. Mawe. 



31. Mya corrugata. M. testa rhombea, viridi; vmbonibus 7'ugosis. 



Linn. Gmel. p. 3221. Mull. Hist. Verm. p. 214. 

 Shell rhombic, green ; unibones wrinkled. 

 Testa ovali viridescente, umbonibus corrugatis, sive rugosis. Chemn. 



Conch. 6. pi. 3. f. 22. a. b. 

 Schroter Flussconch. t. 9. f. 3. Encyclop. Method, pi. 248. f. 6. 



This shell is of a grass-green colour, remarkably 

 corrugated near the hinge, and radiated down the sides. 

 It is thin, pellucid, and whitish, beneath the epidermis ; 

 the inside is marked with fine radiated striae ; the teeth 

 of the hinge resemble those of the M. Pictorum. It 

 inhabits the rivers of Coromandel, and is from three- 

 quarters, to an inch and a half broad. 



