TWO SPECIES OF PARASITIC MITES. 341 
anus is present as a longitudinal slit on the posterior end of the 
body. 
The sexual aparatus is situated between the insertions of the 
fourth pair of extremities, and is composed of two bands of chitin 
running backwards along the ventral surface, each having the appear- 
ance of two segments of circles placed end to end, one behind the 
other, the posterior including more of the circumference of the circle 
than the anterior. Between these two longitudinal bands the penis 
is present as an elongated cone, directed towards the posterior end of 
the body. Epidermal appendages are very poorly represented, the 
only ones of any importance being two long bristles which arise one 
on each side from the posterior end of the sexual chitinous bands; 
and extend a considerable distance beyond the hinder end of the 
body. Besides these there are the small bristles or hairs on the legs 
which have been already mentioned. 
The structure of the female is exceedingly simple, having the 
appearance externally of a minute white ball, with the sub-rec- 
tangular rostrum projecting from its anterior surface. The feet, 
which occupy the same positions as in the male, are, however, very 
much smailer and quite useless for walking on a level surface, though 
probably very effective in boring through the soft tissues of the ear 
of their host. They are composed of but two short joints, the first 
of which is almost immovable, and is united by a triangular chitinous 
base of attachment to the skin of the body; the second is of a 
rounded triangular shape, and is movably articulated to the first. 
Epimera are present, but are very small, their place being taken 
functionally by the chitinous base of the legs. The surface of the 
body is smooth, no bristles or spines of any kind being present either 
at the posterior end or on the diminutive legs. The anus is at the 
hinder end of the body. The opening from the oviduct is in the 
form of a simple transverse slit on the ventral surface, a short dis- 
tance behind the base of the rostrum. 
The course of development of this aberrant form of itch-mite is 
very peculiar, for though in its adult condition it bears considerable 
resemblance to Dermatoryctes fossor, so carefully described by Prof. 
Ehlers in Zeit. f. w. Zool. Bd. XIX., yet it differs essentially from 
this latter, in the fact that the larva closely resemble in general form 
the adult female rather than the adult male, thus leading one to 
suppose that the male was a farther development of a mite like the 
