102 MYA. 



It derives its trivial name from its property of re- 

 flecting, in particular lights, strong prismatic colours. 



SUBSTRIATED GAPER. 



22. Mya substriata. M. testa subovali, alba, subpellucida> longitudi- 

 naliter obsolete striata. 



Shell suboval, white, subpellucid, with obsolete longitudinal striae. 

 Mont. Test. Brit. Suppl. p. 25. (Ligula substriata.) 



The outside is marked with distant elevated striae ; 

 the inside is plain and the margin smooth ; the hinge 

 has a slight projection inwards. The shell measures 

 one-tenth of an inch in diameter. It was discovered, 

 among corallines, by Mr. Montagu, on the coast of 

 Devonshire. It is extremely rare. 



DUBIOUS GAPER. 

 PL 25./. 2, 3. Dr. Coombe. 



23. Mya dubia. M. testa subovali, hiante; cardinis dente obsoleto. 

 Linn. Trans. 8. p. 33. 



Shell gaping and suboval ; hinge with an obsolete tooth. 



Penn. Br. Zool. 1812. vol. 4. p. 165. pi. 47. Da Costa, Brit. Conch. 

 p. 234. Chama parva. Donov. Brit. Shells, t. 108. Pult. in 

 Hutch. Dorset, p. 27. t. 1. f. 1 1. Mont . Test. Brit. p. 28. item Suppl. 

 p. 20. M. Pholadia. 



It has been doubted whether this shell does not 

 belong to the genus Pholas; but Dr. Maton very pro- 

 perly remarks, that, notwithstanding its habits and ap- 

 pearance are like those of a Pholas, it wants the essen- 

 tial characters of that genus, viz. the accessory valves, 

 and therefore must be necessarily placed among the 



The shell is of a light brown colour, thin, brittle, 

 opaque, and marked with fine concentric strise ; the 



