44 Wo7^ms. 



the Larva called the Silk-Worm^ passes first into the state of Chry- 

 salis, and afterwards, at the expiration of about two months, into 

 that of the Parent Fly. It would seem that no other Nidus in Na- 

 -turc, hath hitherto been discovered for the Larva of two species of 

 the Genus (Estrus, except the Stomach of the Horse-Tribe ; although 

 the immortal Linnccus fell into the errof of supposing, that the spe- 

 cies found in the backs of horned Cattle, was the same that is met 

 with in the stomach of Horses. 



'' Habitat (says the great Naturalist) in Ventriculo Equi ct Bourn 



•Dorso." But a reference to Mr. Clarke's beautiful Plate, which ex- 



Jiibits in a most striking manner, the difference between the Larvae. 



^.^nd especially between the Parent Flies, will satisfy every reasonable 



-doubt upon this subject. 



The Eggs of one of these species of (Estrus, may frequently be 

 seen in great numbers, upon the inside of the knee, the side and 

 back part of the shoulder, and on the extreme ends of the hairs of 

 the mane ; but always within the reach of the tongue of the Animal. 

 And although it will rarely happen, that Horses which are not turned 

 out to grass, will have Bots in their stomachs, yet, as Mr. Clarke 

 observes, this may occasionally take place, from the circumstance of 

 one Horse performing the friendly office, of licking another. 

 Mr. Clarke informs us '' he once supposed that the Eggs were 

 loosened from the hairs, by the moisture of the Horse's tongue, 

 aided by its roughness, and were conveyed to the stomach, where 

 they were hatched ; but on a more minute search he did not find 

 this to be the case, or at least only by accident. For when they 

 have remained on the hairs four or five days, they become ripe, after 

 which time, the .slightest application of warmth and moisture, is 



