G. H. F. Nuttall, W. F. Cooper and L. E. Robinson 1H7 
The surface of the body exhibits a number of constantly occurring 
and well-defined grooves: these are the external indications of the 
lines of insertion of bands of muscle-fibres which run in a dorso-ventral 
direction through the body and are attached at either end to the 
chitinous cuticle. On the ventro-lateral margins of the body, posterior 
to the coxae of the fourth pair of legs, are situated the paired spiracles, 
a pair of more or less circular, slightly raised plaques of paler colour 
than the surrounding integument: in the larva, the spiracles and 
tracheal system are not developed. The posterior contour of the body 
is deeply indented at regular intervals by short grooves; these run 
round the margin from the dorsal to the ventral surface and define 
certain small rectangular marginal areas which are termed festoons in 
descriptive nomenclature. It is worthy of notice that the festoons are 
frequently more or less obliterated in the female and immature stages, 
by the distension of the body after engorgement, but although the 
alteration is not so marked in the male, the appearance of the festoons 
differs considerably in the unfed and gorged individuals (PI. XIII). 
The cuticle of the tick is perforated by numerous pores of various 
forms which serve as a means of communication between certain 
modified hypodermal cells and the exterior. Numerous hairs are 
distributed over the different parts of the body; these differ among 
themselves according to their various functions. Certain areas of the 
body are glabrous. 
The sensory organs are comprised of (1) certain defined areas 
into which numerous fine pores open, and beneath which the hypo- 
dermal layer is specially modified : such organs are found in the female 
on the dorsal surface of the basis capituli ( porose areas), and in both sexes 
on the dorsum, where a pair of minute perforated areas are found, to 
which the name of foveae has been applied; these foveae the authors 
have found to exist in the nymph but not in the larva : (2) Haller s 
organ, a complex cavity in the cuticle of the tarsal portion of the first 
pair of legs, which communicates with the exterior by a minute slit¬ 
like pore and bears on its floor a number of sensory hairs, but does not 
contain otoliths 1 : (3) tactile hairs of different forms, arranged either in 
a scattered manner or collected into groups. 
The tactile sense appears to be the most highly developed, after that 
the olfactory sense, and in spite of the absence of eyes, as found in some 
genera of Ixodoidea, H. punctata is very sensitive to light and in- 
1 We intend to publish an account of the general structure of “Haller’s Organ” in 
different species, in the near future. 
11—2 
