ROSTELLARIA. 



TESTA turrita, vel fusiformis, basi acuta. La- 

 bium externum plus minusve aetate dilatatum^ 

 vel integrum, vel dentatum, vel digitatum, 

 basi lacuna canali contigua instructum. Aper- 

 tura oblonga, supern^ in canalem elongatum, 

 supra spiram, extensa, infra in canalem acutum 

 desinens. 



The Lamarckian Genera Rostellaria, Pterocera, and Strom-' 

 JbuSy with a very few shells from other Linnean Genera^ 

 form together that very natural family which Linne de- 

 signated by the generic appellation of Strombus. Perhaps, 

 also, the Struthiolaria should be added to this family. We 

 have endeavoured to modify and amplify the character of 

 Rostellaria in such a manner, as not only to include all 

 the species that Lamarck intended to combine together, 

 but also so as to show the permanent distinctive charac- 

 ters between it and the allied genera ; and in doing so, 

 we have been obliged to admit as a character of the 

 Genus^ the generally elongated^ always distinct, canal, 

 which runs up the spire ; this canal is, indeed, observable 

 in two or three Strombi, but those have always another 

 mark of distinction. As it appears necessary for the 

 purposes of science that genera should be defined, we 

 have retained in our definition of this Genus, such cha- 

 racters as will still include the Str, Pes-Pelecani, though 

 we confess that we think that and its cognate species 

 might very well have been separated from the Rostel- 

 lariae, as forming a new Genus. We have not ventured 

 upon such a separation, because we wish as much as pos- 

 sible to avoid innovation, where it is not imperiously 

 called for. 



Our knowledge of the RostellaricB is confined to the 

 shell itself, excepting that we have the operculum of the 

 R. Pes-Pelecani, which resembles that of the Pterocerata 

 and the Strombi. 



