258 MARINE SHELLS 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



Animal — pale, more or less distinctly lineated, or 

 clouded with black; foot rounded, almost orbicular, 

 hardly as long as the shell is broad ; above with four 

 more or less distinct, black, parallel lines ; rostrum 

 dilated, truncated, tip with four black lines, a black 

 band connecting the eyes: eyes prominent, appearing 

 to be placed on a tubercle at the outer base of the ten- 

 tacula, black with a white orbit; tentacula with 

 darker or black lines, setaceous, and longer than the 

 breadth of the rostrum; beneath immaculate. 



I found this species in great plenty, inhabiting St. 

 John's river in East Florida, from its mouth to Fort 

 Picolata, a distance of one hundred miles, where the 

 water was potable. It seemed to exist equally well, 

 where the water was as salt as that of the ocean, 

 and where the intermixture of that condiment, could 

 not be detected by the taste. Its movements are re- 

 markably slow. 



Class, 



CONCHIFERA. 



OSTREA, Lin. Lam. 



O. *semicylindrica. Shell elongated, semicylin- 

 dric, white, covered with a fuscous epidermis ; sides 

 parallel; base and tip rounded, equally obtuse; in- 

 ferior valve very convex ; superior valve flat : within 

 white, somewhat perlaceous; muscular impression 

 large, white. 



