80 THE ELEMENTS 



In Turton's Linne 182 species of 

 Mu rices are described ; and twenty- 

 two species have been ascertained to 

 inhabit the British seas. 



Genus 27th— -TROCHUS. Ani- 

 mal a Limax : shell univalve, spiral 

 more or less conic; aperture some- 

 what angular or rounded, the upper 

 side transverse and contracted ; pillar 

 placed obliquely. Linn, Syst. 326. 

 Plate 8th, fig. 27th. 



Linne divides the Trochi into three 

 families : *Umbilicate, erect, with pil- 

 lar perforated ; **Imperforati, imper- 

 forate, erect, with the umbilicus 

 closed ; ***Turiti, tapering, with an 

 inserted pillar, and falling on the side 

 when placed upon the base. 



Habitation. The Trochi have 

 mostly been found to inhabit the 

 ocean, with a few land species. They 

 most frequently live near the shore in 

 pools, or such places as are always 



