TWO SPECIES OE 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 smaller and quite useless for walking on a level surface, though 

 probably veiy 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 imnfovable, 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 uf 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 



