347 
ON THE STRUCTURE OF THE SPIRACLES OF A TICK— 
HAEMAPHYSALIS PUNCTATA, Canestrini and Fanzago. 
By G. H. F. NUTTALL, F.R.S., W. F. COOPER, B.A. 
and L. E. ROBINSON, A.R.C.Sc. 
Plates XXII, XXIII. 
The detailed structure of the spiracles in the Ixodoidea has 
hitherto received little or no attention at the hands of zoologists; 
at the same time, these organs are sufficiently extraordinary to make 
it a matter of surprise that, so far as our knowledge of the literature 
goes, not one of the numerous contributors to the subject of tick 
anatomy has found it worth while to undertake a complete description 
or to publish figures to illustrate it. Batelli (1891) gives a short 
account of the structure of the spiracle of a tick, presumably Ixodes 
ricinus, with a single figure, but with this exception we have been 
unable to find any further information on the subject. 
The material for this communication has been accumulated in the 
course of our work on the anatomy of ticks, and in view of the 
interesting features presented by the spiracles, we have preferred to 
publish a separate account of these structures, although a more or less 
general description will appear later in the second part of our paper on 
the anatomy of Haemaphysalis punctata 1 . 
The spiracles are situated in the posterior half of the body, on 
the lateral margins, towards the ventral surface, immediately behind 
and a little external to the coxae of the fourth pair of legs. Each 
consists of a slightly elevated “ plaque ” with a well-defined margin. 
The dimensions of the spiracle show a considerable amount of variation : 
in the adult tick the length of the spiracle usually exceeds the breadth, 
in the nymph the reverse is the case. The following table gives the 
1 See this volume, pp. 152—181. 
