338 CHITONID^. 



looked by most writers, is also comparable with that of Patella 

 vulgata (simultaneously examined and figured), though by no 

 means identical. The cephalic ganglia appear to be suppressed, 

 forming another evidence of the degeneration or want of develop- 

 ment of the cephalic region of this group. 



The above characters are mostly as given by Mr. Wm. H. Dall 

 (Proc. Nat. Mas.^ 1, 288), who has very carefully studied the 

 Chitons. He has published an elaborate classification of the 

 group, mainly based upon characters of the valves and their sur- 

 rounding girdle — a classification which is largely founded u.pon 

 the studies of the late P. P. Carpenter. I have adopted the 

 groups of these eminent naturalists almost throughout, but not 

 usually with the values originally assigned to them, believing 

 that most of their genera had better, at least for the purposes of 

 the present Avork, be considered subgenera. The Chitons are 

 constituted an order, Polyplacophora, b3' Gill, Dall, etc., the 

 main character of which is derived from the divided shell ; this 

 is the principal distinction from the lipapets, with which these 

 mollusks have many points of analogy. Hubrecht forms for the 

 Chitons, etc., a class Amphineura, embracing the orders Soleno- 

 gastres and Chitones. 



Chiton, Linn, 



Etym. — Chiton, a coat of mail. 



Distr. — More than 250 species are known ; they occur in all 

 climates throughout the world ; most abundant on rocks at low- 

 water, but frequently obtained by dredging in 10-25 fathoms. 

 8onae of the small species range as deep as 100 fathoms. 

 North and South America, West Indies, Europe, South Africa, 

 Australia, New Zealand, and Sitka. Fossil, 50 sp. Silurian — . 

 C. squamosus, Linn. (Ixxxv, 5*7). 



The generic description is equivalent to that of the family. 



Mr. Guilding says of the West Indian species (and his remarks 

 will in most particulars apply to others), " They seem to feed 

 entirely by night. Though they remain stationary during the 

 daj^, when disturbed they will often creep awa}^ with a slow and 

 equal pace, often sliding sideways, and creeping under the rocks 

 and stones for concealment. If accidentally reversed, they soon 

 recover their position by violently contorting and undulating 

 the zone ; and for defense they sometimes (when detached) roll 

 themselves up like wood-lice. Some of the larger kinds, espe- 

 cially of Acanthopleura, are eagerl}^ devoured by the lower orders 

 in the West Indies, who have the folly to call them ' beef;' the 

 thick fleshy foot is cut away from the animal and swallowed 

 raw, while the viscera are rejected. We have here a large pale 

 Chiton, which is said to be poisonous." Ladies who are not 

 good sailors, and are fond of trying new preventives against 

 sea-sickness, may (if they can) swallow raw Chitons, and 



