SIGARETUS. 



GENERIC CHARACTER. 



Shell ear shaped, univalve, spiral, depressed : aperture 

 very large, entire, embracing a portion of the preceding volu- 

 tion, much wider than long; destitute of nacre : columella 

 short, spiral : labrum simple : volutions two or three: 

 muscular impressions two, distant: operculum none: a 

 revolving slightly elevated line on the inner surface : spire 

 lateral : periostraca none. 



OBSERVATIONS. 



There are marine shells, inhabiting various parts of the 

 globe. Like Ovula, Oliva, &c., the shell is included with- 

 in the mantle of the animal. Of the few species yet dis- 

 covered, Linne considered one a Helix. Lamarck adopted 

 the name of the genus from Adanson and placed it in 

 his family of Macrostomes, with Stomatella, Stomatia and 

 Haliotis, distinguishing it from the others by being desti- 

 tute of nacre. lie says, it seems to have some relation to 

 Natica: and indeed some similarity is exhibited by the S. 

 concavus of that author, and an allied fossil species which 

 Mr. Hoeninghaus sent me under the name of canalicula- 

 tus. But as those shells are external, or not enveloped in 

 the mantle of the animal, the relation must be considered 

 as of analogy rather than of affinity. 



Cuvier, who examined the structure of the animal of a 

 species of this genus, but we are not informed which. 



