49 



MONOGRAPH OF THE GENUS 



lANTHINA. 



Generic Character. — Testa tenuis fragilis subglobosa 

 plus minusve angulata purpurea; apertura subtrigona, labio 

 externo versus medium sinuato ; columella rectiuscula, sub- 

 tortua, infra producta, rotunda vel subangulata ; apice oblique 

 retrorso. Operculum nullum. — The shells of this genus have 

 attracted much notice, partly on account of the habits and 

 appliances of the mollusc which produces them, and partly for 

 the rich purple colour of their shells, corresponding with that 

 of the purple dye secreted by them. The lanthinge float on 

 the surface of the Atlantic and Pacific Oceans, supported by a 

 float of bubbles, on which are suspended the eggs and fry. 

 They have no specific shore habitats, being only driven in 

 occasional shoals on land by stress of weather. Three or 

 four species have thus been occasionally washed upon British 

 shores. Notwithstanding the remarks of the late Mr. Reeve 

 on the distinctness of the known species of lanthina, it must 

 be remarked that many of the species introduced in the 

 Iconica cannot be defined, points of texture and linear 

 distinctions of form not being reliable. The four or five 

 species into which, for convenience, we may divide the 

 lanthinse of the more angular section still tend to pass into 

 each other by gradations which render it extremely difiQcult 

 to sort a number of specimens ; an experiment which I have 

 tried with the late Mr. Taylor's collection of lanthinse from 

 all parts of the world. 



