s 



247 



most species the beak of the shell is somewhat curv- 

 ed, and short in comparison to the length of the spire, 

 while in others it is straight, and as long, if not longer 

 than the upper part of the shell. Young shells never 

 have the lip dentated. The R. rectirostris, which is one 

 of the most rare shells known, has been admirably fi- 

 gured by Swainson in his Exotic Conchology, from a 

 splendid example in the choice cabinet of W. J. Bro- 

 derip, Esq. 



Rostellaria curvirostris Rostellaria rectirostris 



Rostellaria pespelicani. 



[And three fossil species.] 



PTEROCERA. 



STROMBUS CHIRAGRA. Linn. 



Mawes Linn. pi. 25,/. 4. 



The shells of this genus have not the canal at the base 

 shortened or truncated, as in the Strombus, but on the 

 contrary it is elongated in the form of a tail, attenuated 

 to its extremity, and often closed : the right margin di- 

 lated by age into an expanded digitated wing, attach • 

 ed to and covering the whole of the spire, the lower 

 part interrupted by an interval or wide gap; this 

 space or gap is not contiguous to the body of the shell, 

 (as in the Rostellaria), but distant, aud similar to that 



