304 Mr. Clark'j Obfervat'ions on the Genus Oefrm. 



have not been able to obtain a chryfalis of it for dtlineation ; but it 

 nearly refembks that of CE. hacmorrhoidaUs^ except in fizc. 



There is a confiderable difference between the male and female 

 fly : a de'.ine.ition of each is given, fig. 8 and 9; and to prevent unne- 

 ccfTary repetition, they are defcribed, together with the other fpccies, 

 at the conclufion of the paper. 



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

 the alteration of the Linnxan name Bovis to that of ILqu'i^ as the 

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

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

 felf, had he been in poffeflion of thefe facts, who confidered ti^ivial 

 i\ames 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 unnecefTary 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 

 fituation in the (lomach of the horfe is truly Angular, and is 

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

 pregnated, and the eggs arc fufRcieutly matured, iTie feeks among 

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

 wino-, flie holds her body nearly upright in the air, and her tail, 

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

 in this way (he approaches the part where flie defigns to depofit 

 the e<^"^', 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 fmali diftance, and prepares a fecond egg, and, 



poifing 



