L. E. Robinson and J. Davidson 
27 
general plane of the ventral surface just anterior to the antero-lateral 
angles of the cainerostome. At the level of the last pair of coxae, the 
supracoxal folds diverge somewhat abruptly and, after a short outwardly 
curving course, terminate near the lateral margin of the body about the 
level of the posterior fourth of the body length. The inner or coxal 
folds {cx.f.) run along the mesial margins of coxae I, II and III. They 
terminate anteriorly at the interspace between coxae I and II. Like 
the supracoxal folds, the coxal folds diverge at the level of coxa IV, 
and terminate near the anterior limit of the posterior third of the 
body. 
These integumental folds are always clearly defined and are most 
conspicuous in old starving specimens. Engorgement tends to obliterate 
the terminal portions of the folds. 
In addition to the buccal orifice, already alluded to, the natural 
openings on the surface of the body, common to both sexes of the adult 
stage, are two median, unpaired openings—the genital wpertitre (gen.ap.) 
and the anus (an.). In addition to these, a pair of spiracles (sp.) and 
the two orifices of the ducts of the coxal glands (see PI. Ill, fig. 7, o.cx. 
gl.) open on the ventral surface. The female possesses yet another 
aperture, viz. the mouth of the ovipositing organ, which, in deference 
to its original describer, Nuttall (1908) has termed Genes organ (see 
PI. Ill, fig. 7, o.Gen.orgf This aperture is situated in the camero- 
stome, immediately anterior to the fold formed by the union of the basis 
capituli with the roof of the cainerostome. 
The genital aperture appears in both sexes as a transversely placed, 
ventral opening, situated in the median line, some little distance 
posterior to the basis capituli, opposite the interspace between the first 
and second pairs of coxae. In the second nymphal stage (deuteronymph) 
a small imperforate pit, the Anlage of the future genital aperture, is to 
be found in the same position. 
The anus occupies a position very slightly posterior to the centre of 
the ventral surface. 
The spiracles are situated on the outer portion of the supracoxal 
folds at the level of the fourth pair of coxae. 
In addition to these larger openings the cuticle of Argas persicus is 
perforated by scattered pores. These pores, few in number, are found 
on both dorsal and ventral surfaces, and also on the appendages. They 
are very small and rudimentary. The hypodermal glands, so well 
developed in the Ixodidae, of which the cuticular pores are the external 
openings, are absent in Argas persicus. 
