547 



TANTHINIDiE. 



Swainson, who, whilst he has indulged overmuch in 

 fanciful analogies and gone astray after phantom affinities, 

 has frequently offered suggestions respecting the relation- 

 ship of genera in Mollusks highly worthy of consideration, 

 held that Scissurella had distinct affinities with Iantiiina. 

 The presence of a true operculum in the former genus 

 prevents our associating them in the same family, whilst 

 the point of resemblance between them induces us to 

 regard Ianthlna as the type of a group nearly related to 

 the TrochideE. Often, however, as the animal of this 

 curious genus has been observed, and notwithstanding its 

 investigation by the skilful hand and thoughtful head of 

 Cuvier himself, its affinities have puzzled systematists, and 

 are likely to do so for some time. The position which we 

 assign to it in this work can be regarded only as an 

 approximation towards its true place. Besides the con- 

 nection with Trochus and its allies already indicated, the 

 structure of the apex of the shell would seem to point out 

 an alliance with Chemnitzia, as has been suggested to us 

 by Mr. Jeffreys, whilst the forms and arrangement of the 

 lingual teeth and conformation of the reproductive organs, 

 indicate affinity with Scalaria, further borne out by the 

 power common to the two genera of secreting a purple 

 fluid. 



