MOLLUSCS. 



107 



Fig. 101.— Shells of Vermetus. 



it would seem as if they became depraved, for the shell soon loses its spiral 

 character, and twists about this way and that in the most independent 

 manner; the specimens figured 

 being pretty regular for a Ver- 

 metus. 



The species of Natica have 

 the common name of sea-snail. 

 They are abundant on the whole 

 New England coast, while the 

 other species are found all over 

 the world. The common New 

 England species are large, with 

 rounded, almost spherical shells. 

 They occur on sandy shores, 

 either in estuaries or where 

 they are exposed to the full 

 force of the sea, where they 

 burrow along just beneath the 



surface of the sand, hunting for the clams and mussels on which they feed. 

 Their mode of operation is exactly like that of the drill already described. 

 At the proper season of the year their egg-masses are very abundant, 

 scattered all over the flats, and from their peculiar appearance they excite 

 no little curiosity on the part of the non-scientific. They have the common 

 name ' sand-saucer,' but they differ from a tea-saucer in lacking a bottom 

 and in the fact that the two ends never meet. Held up to the light, one 

 can easily trace in them the different eggs of which they are composed, 

 each appearing as a light spot in the surrounding sandy mass. Their 

 peculiar shape is due to the method of their formation. The eggs, sur- 

 rounded with a sticky envelope, come out in broad sheets from the oviduct, 

 and then pass between the shell and the foot, which by their curvatures 

 mould them into shape. As soon as they pass out, the sand adheres to 

 the sticky surface, and in a short time they become hardened into their 

 permanent shape. 



The cowries [Cijprcea) are tropical shells, possibly the most beautiful of 

 all molluscs. They are covered with a porcelain like enamel, through 

 which the plain, delicate hues or the beautiful markings are seen. Some 

 two hundred species are known, some of which are among the rarities of 

 collections, and in the great sale of 1865, which has already been quoted, 

 specimens of Cyptrcea guttuta and Cijprcea princeps each brought two hun- 

 dred dollars. One species (Cyprcea moneta, the money-cowry) has almost 

 value of itself, for through all the interior of Africa it passes for money. 



