VITRINA. 



TESTA tenuis, liyalina, fragilis, oblonga; spirS, 

 brevi; anfractu ultimo maximo; apertura am- 

 plissima, semilunari, latitudine altitudinem 

 superante, peristomio simplice. Columella 

 linearis, spiralis. 



^^^oT WITHSTANDING tlie remarkable differences described by 

 De Ferussac in the animals of the two shells we have here 

 engraved^ we do not much hesitate to give them as ex- 

 amples of the same genus, partly on account of the 

 extreme similarity between the shells themselves, and 

 partly because De Ferussac's description of the animal of 

 the larger one being taken from a specimen preserved in 

 spirits, it is more than probable that its parts are con- 

 tracted in such a manner as to alter its general appearance 

 very materially; if future discovery should prove the 

 propriety of disuniting them, w^e apprehend De Ferussac's 

 appellation of Helicarion must be applied to the larger 

 one. 



The Vitrinae are very thin, transparent, brittle and 

 glossy shells of an oblong general form ; their spire is very 

 short and compressed, scarcely ever consisting of more 

 than three volutions which increase very rapidly in size, 

 so that the last is very much larger than its antecedent 

 volution, and their aperture is very large, its width being 

 generally greater than its length ; its edges are not thick- 

 ened and it is of an oblong form, having its columellar 

 side deeply emarginate by the last volution : we believe 

 there is no umbilicus in any species, but the columella is a 

 simple spiral line. 



