OF CONCHOLOGY. 63 



by many ; but it is dangerous to eat 

 plentifully of them, unless they are 

 known to be wholesome, as many of 

 them produce very bad effects after 

 they are taken into the stomach. The 

 fresh water muscles are generally 

 found on the surface, or a little way 

 under the mud. Some muscles pro- 

 duce pearls. 



Lamarck divides this genus into 

 three species : Mytilus, Modiolus, and 

 Anodonta. 



In Turton's Linne sixty-four species 

 are described ; and thirteen have been 

 found to inhabit the seas, lakes, &c. 

 of Great Britain. 



Genus 17th.— PINNA. Animal a 

 Limax ; shell sub-bivalve, fragil, up- 

 right, gaping at one end, and fur- 

 nished with a byssus or beard : hinge 

 without teeth, the valves united into 

 one. Linn. Syst. 816. Plate 7tb. 

 fig. 17th. 



