348 
The Spiracles of a Tick 
actual dimensions in both sexes and the nymphal stage, measured on 
ten specimens of each taken from a large number collected in Kent. 
Dimensions of Spiracle in Haemaphysalis punctata. 
Male 
(In microns.) 
Female 
Nymph 
Length 
Breadth 
r 
Length 
Breadth N 
Length 
Breadth 
510 
320 
500 
430 
160 
170 
500 
310 
460 
410 
160 
160 
500 
310 
430 
360 
160 
150 
500 
300 
410 
400 
150 
170 
490 
350 
400 
360 
150 
170 
480 
330 
390 
360 
140 
160 
470 
320 
360 
350 
140 
150 
460 
270 
350 
320 
140 
150 
440 
260 
340 
320 
130 
150 
430 
270 
330 
330 
130 
140 
The contour of the spiracle differs in the three cases, although in 
the case of the male an approach in shape to the female type may 
be frequently observed. The spiracle of the female (PI. XXII, fig. 1) 
is more or less angular in outline, this being due to a flattening of 
the contour of the lateral margin ; that of the male has a more or less 
rectangular figure and becomes gradually narrower towards its posterior 
portion. The spiracle of the nymph is almost circular, with a slight 
rounded angle at the postero-lateral margin. 
The surface of the spiracle is slightly concave with the exception 
of a small central area, the macula (PI. XXII, figs. 1 and 2), dark in 
colour and slightly eccentric in position, situated a little towards the 
antero-mesial margin. The macula is elliptical in outline and placed 
obliquely with the major axis inclined at an angle of about 45° to the 
median axis of the body, the anterior end being directed outwards. 
The marginal portion of the spiracle is formed of dark-coloured chitin, 
and the area between this margin and the macula, of a pale greyish- 
yellow colour, is perforated by numerous regularly-distributed minute 
pores (e.p .); these are best seen by examination of uncleared specimens 
in reflected light. A limited number of coarser pores open on the 
marginal portions of the plate ( m.p .). The macula of the spiracle of 
the female is cleft by a large slit-like opening which we have termed 
the ostium (PI. XXII, figs. 1, 2 os.); the extremities of the latter are 
curved round in a crescentic manner with a convexity towards the 
antero-mesial margin of the spiracle. It is bounded on its external 
