LECTURES ON MOLLUSCA. 43 



down, and inserted, bottom upwards, in the succeeding whirl. The 

 animal has a large foot, with flat, paucispiral operculum, and short 

 tentacles folded sideways. In Torinia, the base is rounded, and the 

 operculum is very singular, being conical, with many whirls. Bifrontia 

 is, as it were, a Torinia rolled out flat. Sometimes the whirls scarcely 

 touch. The mouth is square, as in Solarium. The genus was consti- 

 tuted from French fossils ; but Mr. McAndrew has found it living in 

 very deep water, near TenerifTe, with an operculum and sinistral apex 

 exactly like Torinia. The genus Pliilippia consists of smooth Torinice, 

 with flat operculum. It is said by Philippi to have an animal like 

 Trochus ; but this is probably a mistake, as the apex is sinistral. Dis- 

 cohelix is smooth and flat like Planorbis: it is doubtful whether its rela- 

 tions are with Bifrontia or with Vitrinella. It is found fossil in the 

 American Eocene strata, and living in the Mediterranean. 



A large number of fossil genera are referred to this family by Chenu, 

 but their true place is doubtful. Many Trochids have a large crenu- 

 lated umbilicus, and the characteristic reversed apex can scarcely be 

 observed in the older fossils. 



Three families, differing from each other very much in the shape of 

 their shells, but still having many points in common to distinguish 

 them from the ordinary siphon-bearing univalves, have been separated 

 from the rest of the predacious Gasteropods by Dr. Gray, under the 

 name 



TOXIFERA. 



They have a retractile proboscis : but instead of a separate lingual 

 ribbon, the tube of the trunk is turned in upon itself, and armed with 

 two rows of long barbed teeth, implanted singly in the skin of the 

 fleshy tube. The teeth are curiously formed, resembling the sting of 

 a bee when seen in the microscope ; and probably have more vitality 

 than those of the ordinary type. In some species, the end of the tube 

 is large enough to admit the little finger ; and the creature is able to 

 inflict a decided bite. 



*\ 

 Family CONTDJL (Cones.) 



The Cone-shells are great favorites with collectors, in consequence of 

 their brilliant painting and regular patterns. The Conus gloria-maris 

 has more than once sold for $250. Almost all the species, however, 

 are formed on one plan ; and in the living state, the colors are hidden 

 by a skin, which is often very rough and thick. The animal has a 

 short, strong foot, square in front, and with a large hole underneath, 

 through which water is sponged up. It bears a long narrow opercu- 

 lum, of concentric layers beginning from the point : but if it is mended 

 after fracture, the nucleus is in the centre, as in other tribes. The 

 siphon-pipe is long, extended through the notch of the shell. There 

 is always a notch at the other end of the mouth also. The head has 

 two long slender tentacles, with the eyes along their sides. When the 

 proboscis is drawn in, it leaves a funnel-shaped expansion, or veil, in 

 front of the head. This veil is fringed at the end in Tuliparia ; and 



