APOEIIHAIS. 159 



into the distinct siphon characteristic of the canaliculated 

 shells. The three following British species are enumerated 

 as characterized by their shells : — 

 C. reticulakm : of a brown colour, with four granulated 



ridges on the whorls. 

 C. adversim (so named from having the whorls turned in a 

 contrary way to that of the majority of shells) : it is red- 

 dish-brown, with three granulated ridges on the whorls. 

 C. metula : white, elegantly tapering, with three sculptured 

 ridges on the whorls : taken in deep water. 

 II. Aporehais. — Although this genus is now believed 

 to belong to a different group from the Strombid^, among 

 which I have placed them in the ' Thesaurus,' the shells have 

 so much the character of that family that they have always 

 been associated with it ; and as it so happens that in our 

 British seas we have no representatives of the true Strom- 

 hides, we should consequently enjoy no opportunity of in- 

 troducing one or two remarks about them, unless it were 

 taken in this place. 



It has been an inquiry of some interest, what degree of 

 efficiency may be ascribed to the senses of mollusca, judging, 

 as far as possible, from the organs supposed to represent 

 them. The so-called eyes in some molluscs, imperfectly de- 



