OF NATURAL HISTORY. 411 



lar conduct next feafon. This migration of falmons, herrings, and 

 many other fifhes, from the ocean to the rivers or fhores, is of infi- 

 nite advantage to mankind. They fupply us occafionally, and in 

 fbme countries, as Great Britain, and particularly Scotland, with 

 abundance of nouriQiing and luxurious food ; and, if our fifhe- 

 ries were once put upon a proper footing, they would foon confti- 

 tute one of the moft powerful incentives to induftry, and become a 

 great and important fource of national ftrength and profperity. 



The infeSl tribes, though comparatively diminutive, are not defi- 

 cient in artifice and addrefs. With much art the fpider fpins his 

 web. It ferves him the double purpofe of an habitation, and of a 

 machine for catching his food. With incredible patience and perfe- 

 verance he lies in the center of his web for days, and fometimes for 

 weeks, before an ill-fated fly happens to be entangled. One fpecies 

 of fpider, which is fmall, of a blackifh colour, and frequents cottages 

 or out-houfes, 1 have known to live during the whole winter months 

 without almoft the poffibllity of receiving any nourifliment ; for, 

 during that period, not a fly of any kind could be difcovered in the 

 apartment. If they had been fixed in a torpid ftate, like fome other 

 animals, the wonder of their furviving the want of food fo long 

 would not have been fo great. But, in the fevered weather, and 

 through the whole courfe of the winter, they were perfeftly adive 

 and lively. Neither did they feem to be in the lead emaciated. 



The formica- ko, or ant-lion, is a fmall infedx, fomewhat refembling 

 a wood-Ioufe, but larger. Its head is flat, and armed with two fine 

 moveable crotchets or pincers. It has fix legs, and its body, which 

 terminates in a point, is compofed of a number of membranous rings. 

 In the fand, or in finely pulverifed earth, this animal digs a hole in 

 the form of a funnel, at the bottom of which it lies in ambufh for 

 Its prey. As it always walks backward, it cannot purfue any infcifc, 



3 E 2. To 



