128 Dr. J. E. Gray on the Division of Ctenobranchous 



b. Mitrina. Siphon simple at the base ; tentacles close together 

 at the base; mantle enclosed; "teeth broad, many-toothed"? 

 very small at the tip of the proboscis. Mitra, Turris, Imbri- 

 caria. 



c, Porcellanina. Siphon simple at the base ; tentacles close 

 together at the base ; mantle lobes expanded, covering the shell ; 



teeth ? very small ? not to be seen in the only specimen (in 



bad state) I have been able to examine. Porcellana, Persicula. 



The specimen of P. glabella in spirits showed no appearance 

 of the dilatation of the mantle. 



D. Toxoglossa. Teeth on Ungual membrane in two lateral series 

 (1 • • 1), elongate, subulate (fig. 6). 



Fam. 8. Pleurotomid^. Siphon of mantle and canal of 

 shell straight ; mantle and shell often with a slit in hinder part 

 of right side. 



a. Pleurotomina. Operculum ovate, acute; nucleus apical. 

 Pleurotoma, Drillia. 



b. Clavafulina. Operculum semiovate ; nucleus in the centre 

 of the straight front edge. Clavatula, Tomella. 



c. Defrancianina. Operculum none. Mangelia, Defrancia. 



E. Tsenioglossa. Teeth on lingual membrane in seven rows 

 (3 • 1 • 3), central generally toothed, lateral in three series, con- 

 verging, the inner often broad, two outer subulate, versatile (fig. 7). 



Fam. 9. DoLiiniE. Foot small; siphon of mantle recurved; 

 mantle enclosed ; operculum none. Dolium, ? Malea. Tongue — ? 



Fam. 10. Tritoniad^. Foot small; siphon of mantle and 

 canal of shell straight ; shell variced ; mantle enclosed ; oper- 

 culum ovate, annular; nucleus subapical. Apollon, Triton, Per- 

 sona. The teeth of this family have been verified in a dozen 

 species of the three genera. 



Fam. 11. ScYTOTTPiDJE. Foot small; siphon of mantle prp- 

 duced ; operculum none. Sct/totypus*. 



Fam. 12. VelutinidjE. Foot moderate, rounded ; mantle 

 edge inflated, folded on the edge into two canals ; eyes on outer 

 side of tentacles. Operculum none. Velutina, Otina, 1 Marsenina. 



Fam. 13. Naticid^. Foot very large, much produced; shell 



* In Ann. and Mag. Nat. Hist. x. 415. 1852, by a slip of the pen, I erro- 

 neously stated that this animal had no proboscis. 



