Mr. ClaRk'j Olfervations on tbt Genus Oeflrus, 3X3 



chry [alleles of this fly, which I uniformly found under the dung of 

 horfes. They produced the flies, male and female, reprcfented at fig* 

 18 and 19; but not having at that time any idea of writing on this 

 fubject, I unfoitunately threw away the chryfalides. The larva I am 

 at prefent unacquainted with ; but if it inhabited the fauces of the 

 horfe, it would produce fuch troublefome fymptoms as could not 

 eafily efcape the notice of thofe whofe bufinefs it is to attend to the 

 difeafes of cattle. Such a difeafe has, however, never been defcribed 

 by any writer on this fcience; nor, after an extenfive opportunity both 

 in the dead and living fubiect of obferving them,have I ever feen a bot 

 in the fauces. Perhaps the bots of the ftomach having crawled to 

 the fauces in fearch of food might have given rife to this idea, or they 

 may even have accidentally bred there; for there is little doubt thele 

 animals can live in any part whatever of the alimentary canal. 



I am induced to fufpect they inhabit the ftomach, as well as the 

 two former fpecies; but of this we muft at prefent remain in un- 

 certainty, as well as of the manner in which this fpecies depofits 

 its eggs. 



I have given it the name of veter'mus, becaufe beafts of burden are 

 particularly fubjeel: to it, in preference to the erroneous one of nafal/s. 



Of the Oestrus Ovis. 



I procured about the middle of June fome full-grown larva' of 

 the CE. Owj, from the infide of the cavities of the bone which 

 fupports the horns of the fheep. See fig. 14. 



They are nearly as large as thofe of the (JL.Equi, of a delicate white 

 colour, flat on the under fide, and convex on the upper; having no 

 fpines at the divifions of the fegments, though they are provided 

 with tentacula at the fmall end. The other end is truncated with a 



Vol. III. Ss prominent 



