Microscopical Essays. 



379 



and it's wings white ; the two inferior ones of thefe are fo fmall, 

 that they are not eafily diftinguilhed. 



Among the fly clafs thefe reticular eyes are, in different fpe- 

 cies, of different colours ; there are fome which have them brown, 

 others yellow, others green, and others red, and this in all the 

 different fhades of thofe colours. Some of them have alfo the 

 glofs of metals highly polifhed, others afford us a view of change- 

 able colours, and others have arrangements of different colours, 

 fixed and invariable. The eyes of one fpecies of the gad-fly, fo 

 troublefome to oxen, have (breaks of red, green, and brown, 

 placed alternately. 



One would imagine, that as every fly has two of thefe reticular 

 eyes, each compofed of fuch a multitude of real eyes, they could 

 have no occafion for any more ; but fo it has not appeared to the 

 great Being that formed them, for many fpecies are furnifhed 

 with more eyes, which differ both in conflruclion and form from 

 thofe that are reticulated. 



. 



The eyes already defcribed are properly called reticular ones * 

 ►and to avoid confufion, it will be neceffary to defcribe thofe 

 which differ from them by fome determinate name (they are now 

 generally termed the (lemmata) ; thefe, when examined by the 

 bell microfcopes, appear of a perfectly fmooth, gloffy, and 

 polifhed furface, but plain and fimple, without the leaf!: appear- 

 ance of a reticulated texture. They are alfo much fmaller than 

 the reticulated eyes, and may therefore be called, by way of 

 diftinclion, the fmaller fmooth eyes, or the (lemmata. 



Z Z 2 



M. De 



