LEPTOCONCIIUS. 137 



Genus rapa, Klein, 



Shell thin, globosely pyriform, axis perforate, umbi- 

 licus partly concealed by the reflected inner lip ; spire 

 obtuse ; aperture oblong, produced anteriorly into a wide 

 subrecurved canal. 



Stjti. Bulhus, Humph., not Broum. ReLTpeWsi, Swains. 



Ex. R. tenuis, Martini, pi. 14, fig. 8. 



Rapa differs from Rapana not only in the produced 

 canal of the aperture and thin simple whorls, but in the 

 free, reflexed inner lip and moderate umbilicus ; the genus 

 at present is known only from its shell. 



Genus LEPTOCONCHUS, Riippell. 



Operculum none. 



Shell thin, ovate or subglobose ; spire depressed, rather 

 obsolete ; aperture large, oval ; inner lip anteriorly con- 

 torted and truncate ; outer lip thin, rather expanded. 



E.v. L. Peronii, Lamarck, pi. 14, fig. 9. Shell, L. 

 Peronii, fig. 9, a. 



An examination of the animal confirms the statement 

 of Riippell that there is no operculum. The mantle-mar- 

 gin is greatly thickened and fleshy ; the tentacles are 

 small, broad, and united at their bases ; the eyes are small 

 and black, on the outer side of the tentacles, near their 

 tips ; the foot is small, short, obtuse and rounded behind, 

 with a thin, expanded, disk -like lobe in front, and the 

 siphon is obsolete. The genus differs from Campulotus 

 not only in the absence of operculum, but in the shell 

 never forming a long tubular projection of the mouth, as 



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