314 Mr. Clark'j Obfervations on the Genus OeJIrus. 



prominent ring or margin, which ferves the fame purpofe in an in- 

 ferior degree as the lips of the CE. Eju'i and hc^inorrboidalis, by occa- 

 fionally clofing over, and cleaning the horny plate. When this- 

 margin opens after clofmg over the plate, it occafions frequently a 

 flight fn ap from the fudden admiffion of the air. 



When young diefe larva are pcrfeftly wliite and tranfparent, 

 except the two horny plates, which are black. As they increafe in 

 fize the upper fide becomes marked with two tranfverfe brown lines 

 on each fegment, and fome fpots are feen on the fides. 



They move with confiderable quicknefs, holding v/ith the tenia- 

 cula as a fixed point, and drawing up the body towards them. On 

 the under fide of the larva is placed a broad line of dots-, which, on 

 examination with glafles, appear to be rough points, ferving per- 

 haps the double purpofe of affifting their paflage over the fmooth 

 and lubricated furfaces of thefe membranes, and of exciting alfo a 

 degree of inflammation in them where they reft, fo as to caufe a 

 fecretion of lymph or pus for their food. 



I have moftly found thefe animals in the horns and frontal finufes,, 

 though I have remarked that the membranes lining thefe cavities 

 were hardly at all inflamed, v/hile thofe of the maxillary finufes were 

 highly fo. From this I am led to fufpe£l they inhabit the maxillary 

 finufes, and crawl, on the death of the animal, into thefe fituations 

 in the horns and frontal finufes* 



The breeds of thefe, > like the GE. Bbvisy do not appear confined to 

 any particular feafon ; for quite young and full-grown /arv<e may be 

 found in the finufes at the fame time. 



When full-grown they fall through the noftrilsj and change to the 

 pupa ftate, lying on the earth, or adhering bythe fide to a blade of 

 grafs. See fig. 15. 



The fly burfts the {hell of the pupa in about two months. See 



