59 
above details respecting the Oestri, Vol. XV. p. 157 ; and where 
the same circumstance is asserted in respect to the crows also 
di awing them out from the backs of the rhein-deer : Cornices pro- 
sequuntur Rhenonem ut Oestros dorso inhcerentes extrahunt et deglu- 
tiant, quod quamvis Rheno non facile admittit, fatigatus tamen,ferre 
scepius coactus est ut mihi narravit Dn. Er. Fiellstroem in Lapponia 
ipse natus. 
Oestri Cavicoler , or Face-Bots. Of the Oestkus Ovis, or 
Sheep-Bot. 
1 he eggs of this species I have not yet seen, the sheep being 
very shy under their attacks, which renders it difficult to approach 
them near enough to see the actual operation ; the obscure colour 
of the fly also adds to the difficulty. The sheep are exceedingly 
annoyed with them, and to defend themselves get into the roads 
in dry hot weather, and lie down along the dusty ruts, holding 
then heads close to the ground, which makes it difficult for the 
% them ; at other times one finds them standing up, 
with their heads held low, almost to the earth, and the nose 
turned between the fore legs, their nose being nearly in contact 
with the ground. I his mode of defence must render the attack 
of the fly exceedingly difficult; at other times, when in the open 
field, they congregate together, forming a dense compacted mass 
oi phalanx, which, except to the exterior ones, is scarcely acces¬ 
sible to the fly, the noses of the greater part of them pushed 
against each other, or held nearly close to the ground ; in this 
way those placed in the centre must be very secure. 
The manner in which this species deposits its ova, has not, I 
believe, been described ; nor is it easy to see, though close to 
the animal at the time, exactly in what way this is accomplished, 
owing to the rapid motion and obscure colour of the fly, and the 
extreme agitation of the sheep ; but from the actions of the sheep 
