200 
HERBERT OSBORN. 
long and with the antennas situated at the sides midway from 
the posterior to the anterior borders ; behind these are located 
slight eminences upon which may be found the small eyes, 
which are seen with considerable difficulty. At the front of 
the head may be seen the small rostrum or beak, the end of 
which is usually at or near the surface, but which is capable 
of extension and retraction. The end of this beak is armed 
with a double row of recurved hooks (see Fig. i b). The 
function of these hooks is doubtless to fasten the beak firmly 
into the skin of the host, while the true pumping organ must 
consist, as in the Pediculi of a slender piercing tube, though 
we can see only slight indications of this tube within the head, 
and we have not seen it nor do we find any record of its having 
been seen fully extended in this species. Professor Harker 
says the rostrum can be pushed out, but his figure shows only 
the basal portion with the crown of hooks and nothing of the 
tubular parts inclosed within. 
The thorax is wider than long and widest at the posterior 
margin where it joins the abdomen. The legs project from 
the side, are long and stout, and especially adapted to clasp¬ 
ing and clinging to the hair. An extra provision for this 
purpose consists of a double plate having fine transverse 
ridges in the basal joint of the tarsus. This structure appears 
to have been first described by Professor Harker (Agricultural 
Students’ Gazette, vol. I, p. 162). The abdomen differs greatly 
in form and size, according to the degree of distention, which 
accounts for the discrepancies in the different figures of this 
species. It may be called flask-shaped and more or less flat¬ 
tened according to the amount of matter contained in it. 
There is a row of horny tubercles along each side and a row 
of chitinous plates along each side of the upper surface of the 
abdomen. The spiracles are located in the tubercles at the 
sides, and there is one to each of the last six segments omit¬ 
ting the terminal one. In color there is some variation, as 
would be surmised from a comparison of descriptions by 
different authors. The general color of the head and thorax 
is a light brown approaching to yellowish, with touches of 
bright chestnut on the head and legs and margins of the 
