30 
Ai'fjas persicm 
appear to be surrounded by a broad margin which encloses a central 
rounded or polygonal area. In vertical section, all three forms are seen 
to be raised areas of the cuticle, deeply hollowed on the internal surface 
and slightly depressed on the outer surface, the central portion of each 
area thus being biconcave (see PI. Ill, figs, la, 2 a, and 2 h). The 
central area seen by transmitted light in flat preparations is the outline 
of the internal depression. 
The scutellae are each furnished with a very short stout curved hair. 
Many of the marginal scutellae are compound, and bear two, three or 
four hairs, a corresponding thinning of the chitin underlying them. 
The discs resemble the scutellae in the appearance of their section, but 
never bear hairs. The internal surface of their central area is divided 
by a network of fine ridges (see PI. Ill, figs. 1 and 2, im'p.m.) into a 
large number of polygonal areas, these representing the impressions of 
the individual fibres which form the muscle-columns, the extremities of 
which, as already pointed out, find their cuticular attachment on the 
internal surface of the discs. As the disposition of the discs is deter¬ 
mined by the anatomical arrangement of the body-muscles, the subject 
will be more conveniently dealt with in connection with the description 
of the musculature. 
The interstices between the discs and scutellae are filled with softer 
and more pliable chitin, the surface of which is thrown into short, 
irregularly uirdulatiug ridges. 
In the general structure of its details, the integument of the 
nymphal forms agrees with the foregoing description of that of the 
adult. In the neonymph, the discs are few in number, the scutellae 
are not so closely crowded, and in consequence the soft, wrinkled, in¬ 
terstitial integument is more extensively developed. The marginal 
scutellae, on the other hand, are as well-established as in the later 
stages. 
In the larva, the structure of the integument is strikingly different 
from that of the nymphal and adult forms. It shows a closer approach 
to that of the larval integument of the Ixodidae. The scutellae are 
entirely absent, and the discs are represented by a single circular area 
on the middle of the dorsal surface. The cuticle of both dorsal and 
ventral surfaces is covered with fine, more or less parallel ridges which 
bear a slight resemblance to the pattern of a finger-tip impression. 
The surface of the body is scattered with relatively large hairs. The 
ridges of the integument are most pronounced in the posterior portion 
of the body, and to the fact that they are continuous from the dorsal to 
