TROCHUS. 



species that belong to tropical climates are remarkably 

 handsome and brilliant shells when carefully cleaned, 

 but they have all naturally a horny epidermis which hides 

 much of their beauty. 



The fossil species, which are rather numerous, belong 

 to the newer formations, such as the Crag, the Calcaire 

 grossier, and the green sand ; they are also found in the 

 London clay: we have reason to believe that some species 

 occur as low down the series of formations as the Lias. 



Some species of Lamarckian CarocoUae have been 

 placed with the Trochi by Linneans (e. g. the Trochus 

 terrestris of some authors) these are^ however, land shells 

 and have no operculum; we have already stated the 

 characters by which the Pyramidellae may be easily dis- 

 tinguished from Trochus ; but it may be necessary here to 

 state, that the shell, called Trochus telescopiitmhylAnnesLUS 

 is more properly placed by Lamarck with his Cerithia to 

 which it is closely allied. 



Fig. 1. Trochus Granatum. 



u— 



4. nov. spec. 



5. Labeo, Monodonta, Lam. 



6. nov. spec. 



7. Operculum of Tr. Pica. 



