OF THE UNITED STATES. 323 



Length nine-twentieths of an inch. 



"Width four-fifths of an inch. 



Inhabits the southern coast. 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



Is often cast ashore in old wood, which it pene- 

 trates. It hears some resemblance in form to the 

 shell represented in the Encyc. Method, t. 170, fig. 

 5, &c. Its longitudinal sulcus is very similar to that 

 of P. crispata, but in many other respects it is close- 

 ly allied to P. pusillus, and like that species, it is 

 distinguished by two elongated lamellar plates, 

 which cover the sutures of the posterior junctions of 

 the valves. 



Type and Class, 



ANNULOSA CIRRIPEDES. 



Family BALANLDEA. 



*CONOPEA. 



GENERIC CHARACTER. 



Shell sessile, fixed, composed of two cones joined 

 by their bases, the lines of junction carinate each 

 side ; inferior cone entire, attached by its anterior 

 side and tip to marine bodies ; superior cone formed 

 of six united pieces, with an aperture at the summit, 

 closed by a quadrivalved operculum. 



