270 FUNCTIONS AND INSTINCTS. 



floating fuel when the sea is agitated, so that the 

 kindness and foresight of its Maker by giving 

 it wings, for independent motion, and means to 

 adhere to the fuci, when support is necessary to 

 it, or it takes its food has thus provided amply 

 for its enjoyment and sustenance. The great 

 peculiarity of the latter, the Tethys, is a mantle 

 which extends above and beyond the head, like 

 that of some marine goddess, concealing it en- 

 tirely, and forming an ample veil, fringed or 

 undulated at its margin. By the help of this 

 veil they elevate themselves to the surface, and 

 probably sail on the waters. This animal is 

 nearly related to the Laptysia, a kind of sea-slug, 

 like which it lives in muddy places, and ejects 

 a black fluid ; it is very fetid, and its flesh is 

 poisonous. It only rises to the surface in the 

 hot season. 



I shall next notice a tribe of Gastropods, 

 which at first sight, considering the number of 

 pieces of which their shelly covering is composed, 

 seems to belong to the multivalves, amongst 

 which Linne has placed it. It will be readily 

 perceived that I am speaking of the Chiton, or 

 coat-of-mail shell, but when the animal that it 

 covers is examined, it will be found that, not- 

 withstanding its multivalve shell, it really be- 

 longs to the Gastropods. 



These animals are generally found under stones, 

 sometimes they adhere to the surface of rocks, and 



