t'ertainly very nearly tlie same in all. But not to enteii* 

 into anatomical detail^ we proceed to state that the Chiton 

 IS a more or less elongated oblong* hody^ rounded at its 

 extremities^ whose upper edge is surrounded by a coria- 

 ceous skin, (sometimes beset with fine hairs, sometimes 

 with long spines, and sometimes with small tubercles;) 

 whose back is rather convex and covered with a single 

 row of eight testaceous, moveable, imbricated, generally 

 transverse pieces or valves, the sides of which are fixed 

 down by the edge of the surrounding skin; in some specie^ 

 the valves are not all imbricated nor transverse, but the 

 posterior ones are placed at a small distance from each 

 other, and are rather longer than they are broad; these 

 ^re Lamarck's Chitonel/j, which we, therefore, do not think 

 sufficiently different to constitute, for those reasons only, a 

 distinct genus. Lamarck informs us, that some of the 

 species have more, and others fewer than eight testaceous 

 pieces, but we have never seen any such specimens, nor 

 do we think they exist ; and it may be observed, that he 

 only describes a few species, all which he expressly says 

 have eight valves. 



There are many species of Chitones, which are all ma- 

 rine, found creeping on stones and rocks, and attached to 

 various submarine bodies, particularly in the southern 

 latitudes ; several small sorts are common on our shores ; 

 one of the most interesting of these is the Ch. fascularis, 

 v/liich has a little bundle of hairs placed at the lateral 

 extremities of each plate. The largest Chiton known is 

 the Ch. Gigas, found at the Cape of Good Hope, and one 

 of the most curious is the C. spinosus, from the South Seas* 



In our plate we have given. 



Fig. L Chiton spinosus. 



2. Ch. squamosrtSy from the West Indies. 



3. Ch. fctscicitlaris. 



4. Ch. striatus. Nob. Chitonellus striatus, Lam. 



5. The eight detached valves of Ch. eruciformis, Not. Chltonellus laeViS, 



Lain. 



The fossil species are fare ; detached valves are some^ 

 times found in the Calcareous Sand of the heighbom'hood 

 of i'aris, and in our Crag. 



