OF THE LIMNEAN GENERA. 



ORDER FIRST. 



MULTIVALVE SHELLS. 



Animals soft, of a simple structure, and covered with a cal- 

 careous habitation or shell. 



Genus 1.— CHITON. 



Animal a Doris ; shell consisting of several segments or 

 valves, placed transversely on the back of the animal, and lying 

 upon each other at their anterior edge. 



Chiton marginatus. — -The Marginated Chiton. Plate V. 

 fig. 1. With eight carinated valves^ projecting over each other 

 in the form of a beak ; very finely shagreened, and having a broad 

 margin, of a dusky or ash coloured brown ; |ths of an inch 

 long. Inhabits the British seas, under stones. 



The animals of this genus are marine, adhering to rocks and stones, in 

 general near low water raarlc, and are, at first view, very like an Onisciis 



Genus 2 — LEPAS. 



Animal a Triton ; shell affixed at the base, and consisting ot 

 many unequal erect valves. 



Lepasrugosa. — The Rough Lepas. Plate I. fig. 1. (Bal- 

 anus rugosus, Lamarck.) With a sub-cylindric shell, having 

 usually six furrows, which frequently widen towards the top, and 

 terminate in angulated points, sometimes as wide as at the base ; 

 compartments sulcated, often striated longitudinally •, of a yel- 

 lowish colour ; operculum consisting of four rough, angulated, 

 erect valves. 



Lepas tiniinnahubim.— The Little Bell Lepas. Plate V. 

 fig. 2. (Balanus tintinnabulum, Lamarck. ) Shell conical, with 



