92 PTEROTRACIIEIDjE. 



inflata, Eyd. primitia, Gould. 



involuta, Eyd. Quoyi, Eyd. 



Lamanoiii, Eyd. rosea, Eyd. 



Lesueurii, Eyd. turricula, D'Oii 

 Peronii, Lesueur and Blainv. 



Genus OXY GYRUS, Benson. 



Operculum sub-triangular, vitreous, lamellar. 



Shell spiral, cartilaginous, umbilicated on both sides, 

 back rounded, only keeled near the aperture ; nucleus in- 

 volute, sulcated, calcareous; aperture oval, not fissured 

 anteriorly. 



Syti. Ladas, Cantraine. Helicophlegma, D'Orb. 

 Brownia, D'Orb. 



Ex. 0. Keraudrenii, Rang, pi. 09, fig. 6. Operculum, 

 0. Keraudrenii, fig. 6. a. Shell, O. Keraudrenii, fig. 6, b. 



The shell in this genus, with the exception of the chalky 

 nucleus, is nearly membranous; in the recent state it is 

 quite transparent, but when dry, it becomes milky, opaque, 

 and corrugated. 



Species of Oxy gyrus. 



Keraudrenii, Rang. tessellata, Gould. 



Rangii, Eyd. violacea, Gould. 



Fam. PTEKOTRACHEIDjE. 



Tongue short, oblong or triangular ; teeth in three series ; 

 the central transverse, with three recurved cusps; the 

 laterals three on each side, the inner transverse, with a 

 hooked apex, the two outer sickle-shaped. Head elongate, 

 proboscidiform ; mouth with two vertical, semicircular lips ; 



