136 MANUAL OF NATURAL HISTORY. 



lum annular, with an internal process ; shell 

 spiral, hyaline, sub-turreted ; aperture en- 

 tire in front. Marine. 



51. Family. — Macgillivrayias (Macgillivrayiidse). 



Tentacles four (?), nearly equal ; eyes — (?) ; 

 mantle with an elongate siphon in front ; 

 foot large, produced behind ; a float (?) ; oper- 

 culum annular, with an internal process ; 

 shell spiral, sub-globose, horny, sub-pellucid. 

 Pelagian. 



52. Family. — Oceanic-Snails (Ianthinidse). Ten- 



tacles subulate, with pedicles at their outer 

 bases ; eyes none ; foot small, flat, with a 

 vesicular appendage on hind part ; shell 

 thin, turbinate, violet ; aperture sub-quad- 

 rate ; columella straight ; outer lip notched. 

 Oceanic. 



II. ORDER. — Scutibranchs (Scutibranchiata). 



Gills of two series of lamellae, forming one or 

 two series over back of neck, or on under edge of 

 mantle round foot; shell spiral, or symmetrical 

 and conical. 



I. SUB-ORDER. — Peduncle-eyed Scutibranchs 

 (Podophthalmata). 



Eyes pedicelled, separate from the tentacles ; 

 teeth numerous, lateral ones reniform, very numer- 

 ous, crowded. 

 1. Family. — Wreath-Shells (Turbinidse). Foot with 



