The Chitons. Coat-of-Mail Shells 



organs but the mouth. The mantle edge, covers it completely, 

 like a hood. 



The chitons are an ancient family, geologically speaking. 

 Thirty-eight genera, including about two hundred and fifty living 

 species, are distributed over a large part of the world. Nine- 

 tenths of these species live along shore in less than twenty-five 

 fathoms of water, feeding upon the marine vegetation of this 

 zone. Of these forms the greatest number are found under 

 stones, between high and low tide levels, where the bottom is 

 oozy and muddy. Chitons are rarely found on sandy coasts. 

 A few species venture out to loo fathoms' depth; still fewer forms 

 are dredged in mid-ocean. 



The collector of shells needs a few instructions before he 

 goes for chitons. These curious creatures are nocturnal in habits. 

 They congregate by night where seaweeds are decaying, and 

 return on slow foot to rest in certain familiar rock crevices 

 by day. When the stone to which a chiton is attached is lifted, 

 the mollusk seems to be grown fast to it, so strong is the suction of 

 the broad foot. A quick thrust of a blunt knife under the shield 

 is necessary to dislodge it. The disturbed mollusk will curl up 

 into a ball, like a pill bug, if handled now. No use to try to 

 straighten it by force. The stubborn muscles will break before 

 they will relent. But drop the specimen into a bucket of salt 

 water, and it will soon assume its natural position. 



The business-like collector goes prepared, carrying small, 

 smooth wooden slats and a ball of soft cotton twine. He deftly 

 slips the specimens, one by one, to a place on the wet slat, to 

 which they gratefully attach themselves, and are promptly 

 bound with coils of the twine. Thus they are dried in proper 

 position for museum or cabinet specimens. 



The girdle is a muscular belt, which helps to hold the plates 

 in place, and forms the margin of the shield. The leathery 

 covering is variously coloured and marked. It may be striped 

 or marbled, with smooth, horny surface, or covered with down, or 

 scales, or tufted hairs, or stout limy spicules and knobs, like the sea- 

 urchins. Sometimes the margin has a deep posterior slit or notch. 

 Sometimes the width is so great that the plates are entirely 

 covered over by the girdle. In other forms the girdle is narrow. 



The Californian coast is the best place to study chitons 

 alive. The greatest variety to be found in any one region is 



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