20 
NATURAL HISTORY. 
[east. ZOOL. 
position of the eyes, and subdivided by the number of rows of teeth 
on the lingual membrane. The greater part have the eyes on a 
tubercle on the outer side of the base of the tentacles. 
Table 3 to 7. The families which have three rows of teeth on the 
tongue, and the outer teeth versatile, as the Cassidulidce, Muricidcs, JBuc- 
cinid(E, PusionellidcBj Turrisidce, which have a shell like the Mitres, 
but have a very different animal with more carnivorous habits. The 
Olives ( Olividce), the Harps (^Harpidce), and the LaraellaricB. which 
have the thin shell enclosed in the thick expanded mantle of the 
animal. 
Table 8. The families FasciolaridcB, Persian Cai’pets, and Turhi- 
nellidce, or Turnip Shells, and Mitres {Mitridce), which have three 
rows of teeth, but the outer teeth are fixed like the centre ones. The 
shells have plaits on their pillar lip. 
Tables 9 to 10. The family Volutidce or Volutes ; Date Shells (IFar- 
ginella), and Volutomitra, which have only a single series of teeth on 
the centre of the tongue, and the pillar lip of the shell strongly plaited. 
Tables 11 to 13 contain the families which have seven rows of teeth 
on the tongue, like the Rostrum^-bearing Molluscs, but they have a well- 
developed, often very long, retractile proboscis, like all the foregoing, 
and are equally carnivorous. Some have an elongated siphon to the 
mantle to conduct the water to the gill-cavity, and have a canal in the 
front of the mouth of the shell to protect it. The Helmet Shells 
( Cassididce), the Tun Shells (Doliidce), the Tritons and Frogs ( TrU 
toniadce), the Fig Shells (^Sycotypidce) ; the latter differ from all the 
others in the shell being partly covered by the expanded mantle of the 
animal. 
Table 13 contains the families which are without any siphons on the 
mantle, the water entering in a slight fold on its swollen margin, and 
the mouth of the shell is entire without any notch or canal in front, 
like the shells of the herbivorous molluscs, and for this reason they 
have been arranged with them, but their animals are carnivorous and 
exceedingly voracious, even more so than in many of the preceding 
families, as the Velvet Shells ( Velutinidce'), and the Nipple Shells 
{Naticidce'). The Venus-ear {Stomatia) only differs from the Nipple 
Shell in having a small operculum and a very large animal compared 
with the size of the shell, as is often the case with shells having large 
apertures compared with the size of the spire. The genus Neritopsis 
has a shell somewhat like the Naticce, but the animal and the oper¬ 
culum are unknown. 
The families lanthinidce or Violet Shells, and Scalariadae, the 
Wentle-traps or Stair-case Shells, have many series of similar teeth on 
the tongue. These shells have been generally placed with the Flerb- 
eating Molluscs, but they are very carnivorous, and have a retractile 
proboscis, like the Murices, and they emit, like them, a purple fluid 
Avhich has been used as a dye. 
The remainder of the Prohoscidifera have the eyes on the surface 
of the head, between and behind the base of the tentacles. 
The Tornatelles (^Acteonidce) have many rows of similar teeth on 
the tongue, in this respect as in many other points of their organisa¬ 
tion resembling the Bullce or Bubble Shells, but they differ fromVhem 
