€6 PLATE DL. 



Every hufbandman is acquainted with the direful effects produced by 

 the ravages of thole intruders in the vital economy of that ufeful race 

 of creatures, though few are correcTtly acquainted with their hiitory. 

 The Bots, indeed, have never been fufJBciently or properly defcribed 

 till within the laft few years, when the lubjecl was inveftigated by 

 Bracy Clarke, Efq. and it muft be added, with a degree of accuracy 

 highly creditable to himfelf and fatisfaftory to the public The refult 

 of his remarks appeared iirft in a Memoir publiflied in the third 

 Volume of the Linnaean Tranfaftions, and fubfequently in other pub- 

 lications. Thefe obfervations may be truly faid to form the bafis of 

 our prefent knowledge of the Oeftri tribe, than which no race of 

 infects whatever, can be more Strictly deferving the attention of the 

 Entomologist or the obfervation of the Agriculturist. 



In describing the individual fpecies of Oeftrus at prefent under con- 

 federation Mr. Clarke obferves, that about the middle of June he 

 procured feme full-grown larvae from the infide of the cavity of the 

 bone which Supports the horns of the Sheep. They were nearly as 

 big as thofe of the large Horfe-bot, of a delicate white colour, flat 

 on the under fide and convex on the upper, having no fpines at the 

 divifious of the fegments, though provided with two curved hooks at 

 the fmall end : the other extremity is truncated, with a fmall prominent 

 ring or margin, which feems to ferve the fame purpofe, though in an 

 inferior degree, as the lips of the Oeftrus equi and haemorrhoidalis, by 

 occafioually doling over and cleaning the horny plate of refpiration. 



The larvae are perfectly white and transparent when young, except 

 the horny plates, which are black : as they increafe in fize che fegments 

 of the upper fide become marked with two brown tranfverfe lines, 

 and feme fpots are obfervable at the fides. They move with confi- 

 derable quicknefs, holding with the tentacula as a fixed point, and 

 drawing up the body towards them. The under-fide of the body is 

 marked with a broad line of dots, which, on examination with glaffes, 

 appear to be rough points, ferving perhaps the double purpofe of 

 afiiSting their paffage over the fmooth and lubricated faces of thefe 



membranes,, 



