196 BIVALVES. 



(pinos) the dirt or mud ; but the name given it 

 hy British conchologists would lead us to take its 

 derivation from the Latin, pinna, a large feather. 



PINNA Pectinata* 



SPINY SEA WING. 



Specific Character. Shell triangular, oblong, 

 with about eleven longitudinal ribs, having con- 

 cave spines, which increase in size as they ap- 

 proach the broadest end ; the other side desti- 

 tute of ribs, but obliquely striated ; shell thin, 

 pellucid, brittle, of a light brown colour, darker 

 towards the beaks ; inside of a pearly hue ; 

 breadth three inches at the gaping end, which is 

 slightly rounded ; length six inches and a half. 

 This shell inhabits India : it has also been found 

 on the coasts of Dorsetshire and Sussex. 



QUESTIONS ON THE BIVALVE SHELLS. 



1 . Describe the part of a Bivalve shell which 

 unites the two valves. 



2. By what means are the animals able to 

 open these valves ? 



3. What is the meaning of the terms equivalve, 



* Plate X. figure 4. 



