PLATE DL. 27 



membranes, and of exciting alfo a degree of inflammation in them 

 where they reft, fo as to caufe a fecretion of lymphor pus for their 

 food . 



Mr. Clarke obferves, that he has moftly found thefe animals in the 

 horns and frontal finufes, though he has remarked that the membranes 

 lining thefe cavities were hardly at all inflamed, while thofe of the 

 maxillary ilnufes were highly fo ; and hence he was led to fufpeet that 

 they inhabit the maxillary finufes, and crawl, on the death of the ani- 

 mal, into those fituatious in the horns and frontal finufes. The 

 breeds, he prefumes, are not confined, to any particular feafon, as the 

 young and full-grown larva? are found together at the fame time. 



The larva?, when full grown, fall through the noftrils to the ground, 

 and change to the pupa ftate, lying on the earth or adhering by the 

 fide to a blade of grafs : in this ftate it remains about two months, 

 when the fly appears. — -The manner in which this fpecies depofits 

 its eggs is difficult to obferve, owing to the obfcure colour and 

 rapid motions of the fly, and the extreme agitation of the fheep; 

 but from the mode of defence the fheep takes to avoid it, and its 

 manners afterwards, there can be little doubt that the eggs are de- 

 pofited in the inner margin of the noftril. 



The moment the fly touches the noftril of the fheep, the latter 

 fhake their heads violent!} 7 , and beat the ground with their feet, hold- 

 ing their nofes at the fame time clofe to the earth, and running away, 

 earneftly looking on every fide to fee if the fly purfu.es : they alfo 

 may fometimes be feen fmelling to the grafs as they go, left one 

 fhould be lying in wait for them; which if they obferve, they gallop 

 back, or take fome other direction, as they cannot, like horfes, take 

 refuge in the water. To defend themfelves againft its attacks they 

 have recourfe to a rut, or dry dufty road, or gravel-pits, where 

 they crowd together during the heat of the day, with their notes held 

 clofe to the ground, which renders it difficult for the fly, who attacks 

 on the wing, to get at the noftril. 



E 2 Perhaps, 



