90 NATURAL HISTORY. 



roll themselves into a ball before they leap, as does the 

 smaller species of onisci which much resembles them. 

 These called the Mailed wood lice, are blue gray, and 

 rolled up like grains of shot, move about with great ease. 

 This genus was used, in the early times, in medicine. 



SECOND ORDER. 



MOLLUSCOUS INSECTS. 



Among which belong, 



The One-Eye (polyphemus oculus) ; these creatures are 

 extremely small, and abound in stagnant waters, where 

 they swim about most actively ; in size not greater than a 

 flea ; have one large eye, two feelers, and a forked tail. 



The Fork Fleas (daphnia pulex), as large as the head 

 of a pin; congregate in such numbers as to give the 

 waters in which they harbor a red appearance, and if 

 some vegetable filaments are thrown among them, their 

 lively movements can easily be distinguished, as they 

 swim around the new object in ceaseless and innumerable 

 circlings. 



SECOND DIVISION. 



ARACHNOIDES, OR SPINNERS. 



FIRST ORDER. 

 ARACIINIDIANS, OR INSECTS OF THE SPIDER KIND. 



This division includes two orders, namely, such as 

 breathe through lungs, and others, which, like insects, 

 are provided with trachea or spiracles, as mites. 



