OESTRUS. 
363 
mass of the food, into the intestines; and when 
full grown, on dropping from the anus to the 
ground, a dirty road or water may receive them. 
If on the commons, they are in danger of being 
crushed to death, or of being picked up by the 
birds who so constantly for food attend the foot- 
steps of the cattle. Such are the contingencies by 
which Nature has wisely prevented the too great 
increase of their numbers, and the total destruc- 
tion of the animals they feed on. I have once 
seen the larva of this Oestrus in the stomach of an 
Ass; indeed there is little reason to doubt their ex- 
istence in the stomachs of all this tribe of animals.” 
“ These larvae attach themselves to every part of 
the stomach, but are generally most numerous 
about the pylorus, and are sometimes, though 
mtich less frequently, found in the intestines. Their 
numbers in the stomach are very various, often 
not more than half a dozen, at other times more 
than a hundred, and if some accounts might be 
relied on, even a much greater number than this. 
They hang most commonly in clusters, being fixed 
by the small end to the inner membrane of the 
’ stomach, which they adhere to by means of two 
small hooks or tentacula. When they are re- 
moved from the stomach they will attach them- 
selves to any loose membrane, and even to the 
skin of the hand.” 
The body of the larva is composed of eleven 
segments, all of which, except the two last, are 
surrounded with a double row of horny bristles 
directed towards the truncated end, and are of a 
