Microscopical Essays. 



The mouth is a part of the infect to which the naturalift 

 will find it neceflary to pay a very particular attention : Fabri- 

 cius goes fo far as to alien, that without a thorough knowledge 

 of the mouth, it's form, and various appendages, it will be im- 

 poflible ever to discriminate with accuracy one infeft from an- 

 other. In the ftruclure of the mouth confiderable art and wif- 

 dom is difplayed : the diverfity in the figure is aim oft as great 

 as the variety of fpecies. It is ufually placed in the fore part of 

 the head, extending fomewhat downwards ; in the chermes, 

 coccus, and fome other infects, it is placed under the breaft. 

 Some infects have their mouths armed with ftrong jaws, with 

 which they bruife and tear their food : however fine and delicate 

 thefe organs may appear, they are really hard, and in fome 

 fpecies fuffieiently ftrong to pierce the hardeft wood. Others are 

 furnifhed with a kind of tube or tongue, at one time moveable, 

 at another fixed : with this they fuck the juices of the flowers.* 

 In fome again the tongue is fo fhort as to appear to us incapable 

 of anfwering the purpofe for which it was formed, and the oeftri 

 appear to have no mouth. 



The roftrum, or probofcis, is the mouth drawn out to a rigid 

 point. In many infects of the hemiptera clafs it is bent down? 

 ward towards the breafl and belly. 



The jaws are generally two in number, fometimes four, and 

 at others more ; they are placed in an horizontal direction : the 

 inner edge, in fome infecls, is ferrated, or furnifhed with frnall 

 teeth. 



The tongue is in general a taper and compact inflrument, ufed 

 by the infect to extract the alimentary juices on which it feeds : 



fome 



