lANTHlNA. 



Lamarck, has four subulate tentacula; but according to 

 Cuvier, only two, which are more deeply forked than those 

 of Murex. 



Shell subglobose, thin, brittle, and rather diaphanous ; 

 its aperture angular at its lower part and at its outer side, 

 where however, the angle formed by the union of the upper 

 and lower halves of the outer lip, is much rounded in most 

 of the species, and somewhat so in the common one; Colu' 

 mella straight and elongated, the inner lip turned back 

 over it. The outer lip formed into an angular sinus by 

 the singular projection of its upper half. 



Several species of this Genus are known at present ; 

 they are all more or less deeply violet-coloured, particu- 

 larly the lower half of the shell ; one species, the lanthina 

 jragilisj ( Helix lanthina^ Linn.) is very common in several 

 parts of the world; it throws out a deep purple liquor 

 upon being touched ; another, the /. exigua^ is, we believe, 

 peculiar to the Mediterranean ; a third, the /. globosa^ has 

 been brought from Madagascar, and a fourth has been 

 found upon some of our own coasts, but it is very rare : an 

 engraving of it is prepared for Leach's British Sheik. 

 Swainson justly observes, that the extreme brittleness of 

 these shells is such, that they are very rarely seen perfect. 



We have never seen any fossil species of this Genus, 

 nor are we aware that any exist ; a fossil is, however, enr 

 ' graved in pi. 10 of Sowerby's Mineral Conchology, which 

 bears a very near resemblance to it ; it is there called Helix 

 carinata, and is said to occur in solid grey Limestone, near 

 Settle; in Yorkshire. 



Fig. 1 lanthina fragilis. Lam. 

 2 exigua, Lam. 



