214 NATICID^. 



assuming a quoit-like form ; it is of a gelatinous 

 consistency, but rendered tolerably firm by the admix- 

 ture of grains of sand. These curious bodies may often 

 be seen lying on the sand at low water of spring-tides 

 in summer. They have been mistaken for zoophytes, 

 and were placed by Solander and Ellis in the genus 

 Flustra, by Pallas in Eschara, and by Lamarck in Dis- 

 copora. '^ The cells are arranged in quincunx order " 

 (Gould). 



The Rev. L. Guilding (Linn. Trans, vol. xvii.) divided 

 this genus into Natica and Naficina, the former having 

 a shelly, and the latter a horny operculum. Gray pro- 

 posed to adopt the genus Neverita of Risso for the 

 species with a horny operculum; but Risso retained 

 Natica for these, and his description and figure of Ne- 

 verita represent a different kind of shell (apparently 

 Natica olla), which has the umbilicus closed by a solid 

 pad. In all our species the operculum is horny. Reeves's 

 list contains 137 recent species of Natica. There are 

 many obsolete generic synonyms. 



A. Shell rather thin, with a produced spire ; umbilicus small. 

 1. Natica Islan'dica"^, Gmelin. 



Nerifa Islandica, Gmel. ed. S. N. p. 3675. Natica helicoides, F. (ill. iii. 

 p. 339, pi. c. f. 6. 



Body pale yellowish-white, minutely and closely speckled 

 with flake-white : syiout broad and large, with rounded cor- 

 ners : tentacles small ; they either project at the sides of the 

 front foot-lobe, or are pressed back by it on the outer lip of 

 the shell : eyes, none observable : foot narrower at the sides, 

 expanded and forming short ear-shaped lobes in front, thicker 

 and folded back behind into an angular point. 



Shell conic oval, less solid than any other recent British 

 species of Natica, semitransparent, not glossy when fresh and 



* Icelandic. 



