SOLEN RAZOR SHELL. 151 



which have a coating of mother-of-pearl in the 

 inside of their valves. Pearls are said to be 

 produced by a disease of the animal, occasion- 

 ing a partial secretion of the substance, which 

 forms the inner coating of the shell. The Bri- 

 tish islands, especially Ireland, have been noted 

 for their pearl fisheries. The Con way was for- 

 merly celebrated for this production : a large 

 one which was taken in that river, and presented 

 by Sir Richard Wynne the chamberlain, to 

 Catherine the consort of Charles II. is said still 

 to adorn the British crown. 



GENUS. SOLEN.* 



RAZOR SHELL. 



Generic character. Shell bivalve, equivalve, 

 oblong, transversely elongated, gaping at both 

 ends ; hinge has a subulate, reflected tooth, 

 sometimes double, not inserted into the opposite 

 valve. Most of the shells are brittle ; some 

 have an internal rib extending from the hinge to 

 the opposite margin. 



* Plate^VIL fig. 3, 4, 5. 



