OF NATURAL HISTORY. 107 



the articulations of which are fo exceedingly elaftic, that the 

 animal is enabled by their means, to fpring to furprifing dif- 

 tances. It has two fine eyes, and its body is covered with 

 cruftaceoiis fcales. The flea is the only infect belonging to 

 this order which undergoes a transformation fimilar to that 

 of the former orders : All the other winglefs infects are pro- 

 duced in a perfecSt 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 nourifhed in boxes, and fed 

 with flies, which they greedily devour. Before changing in- 

 to the chryfalis fl:ate, they live fourteen or fifteen days in 

 the form of caterpillars. Araneay or fpider : This genus 

 comprehends a great many fpecies. The fpider has eight 

 feet^ and an equal number of immoveable eyes. The chief 

 prey of the fpider is flies, animals whofe motions are ex- 

 tremely quick and defultory. To enable the fpider to ob- 

 ferve their movements in every direction, fhe is furnillied 

 with eight eyes, the pofltion 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 fevcral mufcular infl:ruments, 

 fhaped like nipples or teats. Each of thefe contain about 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 ambufh, with aftonifhing patience, till an ill-fated 

 fly is accidently entangled. The fpider, from the vibration 

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

 infl:antly feizes it with his fangs, devours its vitals, and after- 



