L. E. Kobinson and J. Davidson 
20 
The Integument. 
Plate III. 
The integument is comprised of two layers—an inner layer of 
living cells, forming the Jiypodermis, and an external chitinous cuticle, 
a product of the activity of the hypodermal cells. The consideration of 
the structure of the hypodermis and its relations with the superimposed 
cuticle is reserved for a subsequent section of this paper; the presenc 
is only concerned with the cuticular structures. 
To the naked eye, the cuticle of Argas persicus presents the appear¬ 
ance of a leathery investment with a finely granular surface, which is 
interspersed with small, slightly depressed, glistening areas of darker 
colour and rounded or elliptical outline. 
If the cuticle is removed, in the manner described in a previous 
section (p. 23), a complete preparation of the cuticle of the dorsal and 
ventral surfaces may be obtained. From such a preparation it is seen 
that the granular appearance of the cuticle is due to the fact that 
almost the entire surface of the body is divided by a network of fine, 
undulating wrinkles into a mosaic of minute areas (see PI. II, fig. 3). 
These cuticular areas are of three kinds, viz.:— a, the discs ; h, the 
scutellae', and c, the marginal scutellae. The discs (dc.) are most 
conspicuous by reason of their greater size and darker colour. They 
are disposed in regular order over the entire dorsal surface of the body; 
on the ventral surface, however, they are limited to the marginal and 
post-anal portions. Towards the margins of the body, the discs are 
small and numerous, and, for the most part, are arranged in radially 
disposed series. On the median field of the dorsum they are usually 
larger and more isolated. The entire remaining surface of the body, 
with the exception of certain limited portions, is covered by small areas 
—the scutellae (sc.) —which form a mosaic-like filling between the discs. 
The scutellae are absent from the skin of the appendages, the greater 
portion of the coxal and supracoxal folds, the camerostome, with its 
folds, the post-genital area, the perianal area, and a small lozenge-shaped 
area situated in the median line towards the anterior end of the dorsum. 
On both dorsal and ventral surfaces, the margin of the body is outlined 
with a single row of more or less quadrangular areas—the marginal 
scutellae (sc.m.). These differ from the ordinary scutellae in their 
shape, their greater size, and in the fact that they are often comjiound 
As seen by transmitted light, the discs and both forms of scutellae each 
