GASTEROPODA. 



155 



inserted into a tough ligament, which is either wrinkled, 

 granulated, or spiny, forming altogether a boat-shaped 

 shell. Animal, having 

 the head rather indis- 

 tinct ; no tentacula nor 

 eyes, but having a 

 membranous veil, and 

 a long tongue spirally 

 rolled, and armed with 

 horny teeth ; branchiae 

 forming a series of lamellae between the mantle and the 

 foot on each side ; foot long and disk-shaped, rounded at 

 each end. — 194 species*; also fossil. 



The ligament of this shell is either fleshy, smooth, 

 wrinkled, or covered with scales or tufts of hair ; and in the 

 Chiton spinosus and other species, it is armed with nume- 

 rous thin long black spines. The interior of the shell is 

 generally white ; but some are green, and one species is of 

 a beautiful rose colour. They often attain a large size, 

 measuring several inches in length ; but do not usually 

 exceed two inches. They are found in most seas, at low 

 water, on the rocks and stones, but they are removed with 

 difficulty, for they adhere with extraordinary tenacity ; 

 the larger species come from warm latitudes, and several, of 

 a small size, are found on the British coast. They have 

 the power of rolling themselves up into a ball, like the 

 woodlouse or the hedgehog. 



The animals of Lamarck's genus Chitonellus (considered 

 by Philippi as not separated from the above genus) can 

 move with great rapidity, turning their bodies to the right 

 and left as they walk on the stalks of marine plants. 

 " They seem to feed entirely by night. Though they 



* Reeve's leonica. 



