£22 INTRODUCTION TO CONCHOLOGY. 



is, perhaps, enabled to elude their vigilance, from the simi- 

 larity which he bears to a pebble perforated by the 

 waves. 



This curious mollusk presents in his construction the 

 appearance of an oblong hirudiniform mass, without eyes, 

 and possessing a thin membranaceous veil in place of ten- 

 tacula over the mouth, which has a long spiral tongue, 

 furnished with horny denticles. The respiratory organs, 

 selected whereby to characterize the subdivision of the Gas- 

 tropods, consists of a series of pyramidal leaflets, wliich 

 encircle the body, as in Patella, within a depression 

 between the edge of the mantle and the foot. 



Chitons are generally found creeping on the rocks, or 

 closely attached, as the Limpet, to stones or shells, or sea- 

 weeds, and not unfrequently to oysters, on the coast of 

 South Devon. But how, it may again be asked, is this 

 effected, for the Creator has denied to them the disc, or 

 byssus, which distinguishes different bivalves ? — By means 

 of a gelatinous fluid, which exudes from the under surface 

 of the body. It seems the pleasure of the Deity to produce 

 the same results by an infinite variety of means. 



The generic appellation. Chiton, is derived from a Greek 

 word, signifying a man^s tunic, and aptly expresses the 



