27 
curing it. The specimens which I have obtained of its Chrysalis 
have been found upon the ground, or under horse dung ; its ap¬ 
pearance is given PI. I. fig. 12. 
It is fortunate for the animal, or rather we should say it is beau¬ 
tifully ordered and provided, that the Larva of this species should 
make no stay at the edge of the anus, as far at least as we have 
yet observed, and as is the case with the next species ; for it is 
obvious, had it so done, its roughness and more considerable 
dimensions would have rendered it a very serious evil. 
Whether these Larva? can exist in the stomach of a carnivo¬ 
rous animal I am not certain. I gave upwards of a hundred eggs 
(proved by trial to be ripe, and containing a living caterpillar,) 
to a cat in milk at various times ; and on destroying her at 
the end of two months after the first portion had been given, 
no traces of them in the stomach or intestines could be dis¬ 
covered . 
I have once seen the Larva of this Oestrus in the stomach of an 
ass : indeed there is little reason to doubt their existence in the 
stomachs of all this tribe of animals. 
The Larva, when matured and ripe, quits the stomach of the 
animal, and falls to the ground, and finding a convenient place of 
retreat, undergoes its change to Chrysalis, the skin then losing its 
organization, and changing its colour to a reddish brown. After 
remaining torpid in the state of Chrysalis a few weeks, the super¬ 
fluous moisture being removed, and the parts of the future Insect 
being hardened by drying, it bursts from its confinement, and the 
Fly appears making its exit at the small end, (see fig. 13 and 14, 
the male and female,) and the head or face of the Fly very much 
enlarged, fig. 15, and one of its wings magnified, showing the 
distribution of its tendons or nerves, fig. 16. 
On quitting their shell they in a few hours become dry, take 
wing, and then seek their mates. The female being impreg¬ 
nated, searches for a proper subject among the Horses, performs 
