121 
SHEEP. 
Maggot of Sheep Nostril Fly. (Estrus ovis, Linn. 
(Estrus ovis. 
Fly, magnified, with line showing natural length, maggots, mouth-hooks of 
. maggot, and tail segment, showing spiracles, and lobes acting as organs of 
progression, all magnified, after Brauer, see p. 125. 
For some years back I have from time to time received specimens 
of Sheeps’ Nostril-maggots, with various enquiries regarding them, and 
occasionally a statement that the maggots forwarded were found “ in 
the brain,” or “ at the base of the brain,” as the case might be. This 
circumstance seemed very unlikely, nevertheless it appeared worth 
investigating, as I was personally aware that in a locality near London 
the usual buyers of Sheeps’ heads did not like to purchase them 
about May, because of the presence of the maggots (which were 
certainly there), and which I was informed they considered were in 
the brain ; also the presence of these maggots in the brain has been 
mentioned in more than one entomological work, and was alluded to 
by Prof. Eiley as being considered possible, according to the evidence 
of some practical Sheepmen, by means of these larvae making their 
way through the perforations of the ethmoid bone ; of course in this 
case the creature would not get in when it was a thick lumpy maggot, 
about an inch long, but (that is if it did it at all) in its first stage, 
answering to the fine worm-like form in which the Ox Warble- 
maggot cuts and pierces its way down through the thick hide of the 
attacked cattle, to the under or fleshy side. 
During last summer I bestowed the best attention I could in 
examination of Sheeps’ heads affected by staggers or “ gid,” con¬ 
jectured to be caused by Nostril-maggot, and also of the state of those 
with maggot in the nostrils, and can certainly say that there did not 
seem the slightest reason to suppose that the maggots entered the 
brain, or had anything to do with attack of “ gid,” of which the 
common cause is well known; but at the same time there is no reason 
why a sheep should not suffer, both from hydatid in the brain causing 
the gid, and presence of the maggot in the nostrils, at one and the 
