98 THEPHILOSOPHY 



by their means, to fpring to furpriling dlftances. It has two fine 

 eyes, and its body is covered with cruftaceous fcales. The flea is 

 the only infedl belonging to this order which undergoes a transfor- 

 mation fimilar to that of the former orders : All the other winglefs 

 infeds are produced in a perfect ftate either by the mother, or from 

 eggs. The caterpillars of the flea have forked tails, and are very 

 fmall and lively. They may be nouriflied in boxes, and fed with 

 flies, which they greedily devour. Before changing into the chry- 

 falis ftate, they live fourteen or fifteen days in the form of caterpil- 

 lars. — Aranea, or fpider : This genus comprehends a great many 

 fpecies. The fpider has eight feet, and an equal number of im- 

 moveable eyes. The chief prey of the fpider is flies, animals whofe 

 motions are extremely quick and defultory. To enable the fpider 

 to obferve their movements in every diredion, flie is furnifhed with 

 eight eyes, the pofition of which merits attention : Two of them 

 are placed on the top of the head, other two on the front, and two 

 on each fide. The mouth is armed with two crotchets, by which it 

 feizes and kills its prey. Round the anus there are feveral mufcular 

 inftruments, fliaped like nipples or teats. Each of thefe contain a- 

 bout a thoufand tubes or outlets for threads fo extremely minute, 

 that many hundreds of them mufl: be united before they form one 

 of thofe vifible ropes of which the fpider's web is compofed. The 

 figure of the web varies according to the fpecies, or the fituation 

 the animal choofes for its abode. After the web is completed, fome 

 fpecies refide in the center, and others occupy the extremity of their 

 habitations, where they lie in ambudi, with aflonifhing patience, till 

 an ill-fated fly is accidentally entangled. The fpider, from the vi- 

 bration of the threads, perceives his prey, ruflies forth from his cell, 

 inftantly feizes it with his fangs, devours its vitals, and afterwards 

 rejefts the exhaufted carcafe. Spiders prey upon all weaker infeds, 

 and even upon their own fpecies. — The/corpion : This venomous 

 infed is a native of warmer climates than thofe of the north of Eu- 

 3 I'ope- 



