304 Mr. Clark'j Qb/ervaiwns on the Genus Qeflrm* 



have not beert able to obtain a chryfalis of it for delineation ; but it 

 nearly rciembles that of G£. hcvmorrhoidalh y except in fize. 



There is a confiderablc difference between the male and female 

 fly : a delineation of each is given, fig. 8 and 9; and to prevent unne- 

 cdlary repetition, they are defcribed, together with the other fpecies, 

 at the conchifion of the paper. 



Perhaps it will be hardly neceffary to apologize to the Society for 

 the alteration of the Linnaean name Bovis to that of Equi, as the 

 former, if retained, would continue to convey a very erroneous idea; 

 and it would, without doubt, have been changed by Linnasus him- 

 ielf, had he been in pofTefTion of theie facts, who confidered trivial 

 names not as fetters to the fcience, but as temporary conveniences, 

 to be altered or retained as time and further difcovery might prove 

 them to be juft. On the other hand, wanton and un neceffary al- 

 teration, on flight pretences, certainly cannot be too much repro- 

 bated. 



The mode purfued by the parent fly to obtain for its young a 

 frtuation in the ftomach of the horfe is truly lingular, and is 

 effected in the following manner: — When the female has been im- 

 pregnated, and the eggs are fufficiently matured, the feeks among 

 the horfes a fubject for her purpofe, and approaching it on the 

 wing, ihe holds her body nearly upright in the air, and her tail, 

 which is lengthened for the purpofe, curved inwards and upwards : 

 in this way ihe approaches the part where ihe defigns to depofit 

 the egg; and fufpending herfelf for a few feconds before it, fuddenly 

 darts upon it, and leaves the egg adhering to the hair : ihe hardly 

 appears to fettle, but merely touches the hair with the egg held 

 out on the projected point of the abdomen. The egg is made to 

 adhere by means of a glutinous liquor fecreted with it. She then 

 leaves the horfe at a fmall diftance, and prepares a fecond egg, and, 



poifing 



