LECTURES ON MOLLUSCA. 33 



proportion to the size of the animal. It is difficult to say where they 

 find room to deposit it when swallowed. Swainson, who, with many 

 fancies, devoted much time to pointing out the analogies among vari- 

 ous groups of mollusks, paid particular attention to the Mitres. It 

 has already been shown that one group passes into the Muricid. 

 Another possesses the dentition of the Volutes. In the restricted 

 group, the Strigatellas have the aspect of Columbella. They are found 

 under stones at low water, and are generally covered with an epider- 

 mis. Even when living, they are often coated over with nullipore, 

 an evidence of their sluggish habits. The Imbricarias are, as it were, 

 plaited cones, and Cylindra has the shape of the Olives. They live in 

 the sheltered sands of the coral lagoons, and even in the black mud of 

 mangrove swamps. Lastly, the fossil genus Volvaria has close rela- 

 tionship with Marginella. 



Family TURBINELLID^I. ("False Volutes.") 



The Turbinelles are known from the last family by the lateral teeth 

 of the lingual ribbon; which, instead of being saw-shaped, have only 

 one strong horn on each to tear with. The middle tooth, however, is 

 very long and trident-shaped. The shell always has strong, trans- 

 verse plaits in the middle of the pillar lip. The true Turbinelli are 

 pear-shaped, with a long canal. The " shank-shell" is carved by the 

 Cingalese; and when found reversed is considered sacred. The priests 

 make use of it to administer their medicines. The group Cynodonta, 

 of which the two finest species inhabit the tropical shores of Atlantic 

 and Pacific America, are compact, and somewhat triangular in form. 

 The shell looks as if it bid defiance to all enemies, being extremely 

 strong and heavy, armed with stout knobs, and closed with a thick 

 twisted operculum. The animal, however, is said to be timid and 

 inactive, shrinking quickly within its shell at the slightest alarm. 



In the next section there is only one row of teeth on the lingual 

 ribbon, the lateral series being obsolete. The central teeth have gen- 

 erally three lobes, but sometimes they end in a single spike. 



Family VOLUTIDJE. (Volutes.) 



The Volutes are large, showy shells ; most of them rare, and highly 

 prized by collectors. They have a very short spire, with a mamil- 

 lated nucleus, which is sometimes disproportionately large. The bot- 

 tom of the pillar lip is always plaited, with a notch for the breathing 

 pipe, which is short, turned back, and often furnished with little flaps 

 at the base. The foot is generally large, sometimes with a slit on 

 each side near the head, as in the Olives. The tentacles are small, 

 far apart, and joined by a veil. The eyes are on lumps behind the 

 tentacles. 



The Boat-shells and Melons are large and thin, with very expanded 

 mouth, and a few sharply-cut pillar-plaits. They are, as it were, 

 Marsupial animals, the eggs being hatched within the mother's body, 

 and the young ones living there till they are more than an inch 

 long. The Oymbas are almost exclusively West African shells. They 

 were called Yet by Adanson, who tells us that the high winds some- 



