OF MOLLUSCA. 47 



ample ; mantle edge simple ; lingual membrane short, linear ; cen- 

 tral tooth unidentate ; lateral teeth 3 • 3 ; inner broad, toothed ; two 

 outer simple, hooked. 



The animal of Naticida has a very large foot, elevated behind 

 and enveloping a part of the shell, and produced in front, separated 

 on the sides by a transverse groove. 



Between the front lobe and the shell is placed the head, which is 

 more or less hidden, broad and depressed, and provided with flat 

 conical tentacles. — If Orb. A. M. 400. 



Central tooth of Natica pul- Fig. 27.— Naticapulchella. 



chella strong, wide at the base ; 

 lateral process on each side short, 

 thick ; cutting edge longly re- 

 curved, with three pointed lobes, 

 the middle one largest ; lateral 

 teeth first stretched out at the tip and recurved, the middle point 

 larger, the outer smaller and minutely denticulate within, second and 

 third short, claw-like (fig. 27). — Loven. 



The Natica are very voracious, and play a conspicuous part in 

 devouring the dead fish and other animals thrown up by the tide. 

 They have the power of perforating shells with a small round hole, 

 and through the aperture they extract the juices and destroy the 

 lives of the otherwise secure inhabitants. 



Their foot is very large, so as completely to envelope the object on 

 which they prey. They burrow in the sand, so as to be almost entirely 

 concealed by it, and their place is generally indicated by a small heap 

 of sand. 



The singular nidus in which the animal deposits its egg has been 

 an object of much curiosity and speculation. It is a mass of sand 

 glued together into the shape of a broad bowl, open at the bottom 

 and broken on one side. The thickness is about that of orange- 

 peel, easily bent without breaking when damp, and when held up to 

 the light will be found to be filled with little cells arranged in quin- 

 cunx order. Each of these cells contains a gelatinous egg having a 

 yellow nucleus, which is the embryo shell. It is found plentifully 

 about midsummer on every sand-flat where any species of Natica 

 resort. It has been considered as a coral, and called Flustra are- 

 nosa, Eschara lutosa, Alcyonium arenosum, and Discopora crebrum ! 

 —Gould, Mass. 233. 



The' small Natica are often found in the stomachs of fish. 



Natica have been said to be without any epidermis (or peri- 

 ostraca), but tbis is an error ; it is found on all these as on all other 

 shells. Many Northern Natica even have a thick hard periostraca. 



a. Naticina. 'Shell subglobose, solid; aperture moderate. Oper- 

 culum large, horny, with a calcareous inner layer. 



1. Natica. 

 Shell hemispherical, or half-ovate, solid ; spire short ; mouth half- 

 ovate ; inner lip flattened. 



