TWO SPECIES OF PARASITIC MITES. 2313, 
the outline of the body, or rather circle round the anus, which, in 
this species, is placed almost in the centre of the back. As the 
folds approach nearer the anus they become less and less continuous, 
becoming first rows of rounded papillae, and then disappearing 
almost altogether. Towards the anterior end of the dorsal surface 
and near the median line are two short spines, one on each side ; 
and a somewhat shorter one is present on each side near the lateral 
margin. On each side of the anus there are two curved rows of 
short, blunt bristles, forming a kind of double arch over it, and 
made up, the outer one of four, the inner one of two bristles on 
each side. These point in a general way backwards and inwards 
towards the anal opening. Anal bristles on the posterior end of the 
body are entirely wanting. 
The dorsal position of the anus is very peculiar, and it was this 
that suggested the name “notoédres,’ which Bourguinon and 
Delafond applied to this species. It is strange that the peculiarity 
should have escaped the notice of earlier observers, as it is very 
well-marked, Fiirstenberg, who has given some very fine figures of 
this species, takes no notice of the dorsal opening, but indicates an 
opening on the ventral surface where none exists. 
At the anterior end of the body is situated the rostrum, composed 
of the following parts: A pair of biting three-jointed mandibles, 
the third joint springing from the side of the second and growing 
out to an equal length with it, the opposed edges being furnished 
with blunt serrations, thus forming strong nippers on each side of 
the mouth. Below these are the immovably united maxillae with 
their three-jointed palps, which extend forward parallel with the 
mandibles. A thin fold of the integument surrounds the whole, 
enclosing it in a kind of sac open in front, called by Robin the 
camerostomum. Viewed from the dorsal surface a portion only of 
the rostrum is seen, as it is partially covered by a fold of the skin 
which projects over it. 
The body is provided with four pairs of five-jointed legs, two 
anterior and two posterior, the anterior arising from the antero- 
lateral margins of the body, the posterior from the hinder portion of 
the ventral surface. The first four joints of these legs are surrounded 
and strengthened by rings of chitin of a more or less irregular 
shape, and are armed along their sides with bristles whose positions 
are constant in the same species. The fifth joint is covered with a 
