INDEX TO PLATES. 



(From American Conchology.) 



astarte castanea. 

 Pandora trilineata. 

 Oliva litterata, Lam. 

 Unio triangularis, Barnes. 



" suLCATus, Lea. 



" ridibundus. 



" monodonta. 

 Dklphinula LAXA. 

 Melania nupera. 



" " young. 



DEPYGIS, 



Lutraria lineata, 

 Paludina decisa, 



vivipara, L. 

 Anodonta suborbiculata. 

 nucula limatut.a. 



LjEVIS. 



" concentrica. 

 Helix albolabris. 

 " thyroidus. 

 Unto ellipsis, Lea. 

 " subtentus. 

 " undulatus, Barnes. 



" ABRCPTUS. 

 -SOLEOURTUS COSTATU.S. 

 FULGUR PYRULOIDES. 



Glandina truncata, (im. 



Alasmodonta confragosa. 



Unio piiaseolus, Hildreth. 



The lower figures represent the bran- 

 chial oviducts ; that of the middle 

 is a lateral view of a portion, of the 

 natural size, as distended by the 

 included eggs. On the right is^ 

 represented the summits of the 

 tubes of which this organ is com- 

 posed. On the left are two of the 

 tubes magnified, 

 xxiii. Unio tetralasmu.s. 



.\xiv. '* PEHISCENS. 



