34 
Argas jiersicus 
coxae I and II ; in dried specimens, however, it frequently happens, 
owing to the shrinking of the cuticle, that the fold is obliterated and 
the gaping aperture is then quite apparent. 
The actual site of the opening is often demonstrated in a curious 
way. When living specimens are immersed in Carnoy’s fluid for 
fixation, the operation causes the ticks to expel a quantity of the 
secretion of the coxal glands which coagulates in the form of an 
adherent flocculent tuft, immediately on coming into contact with the 
reagent. 
We have not identified the coxal glands in the larva. 
Gene’s Organ. 
A detailed description of the structure and relations of this remark¬ 
able organ, which is only found in the female, is reserved for a later 
section; the present is only concerned with those parts which are 
visible on external examination. 
The external opening of Gene’s organ is situated in the lower part 
of the camerostomal depression, immediately anterior to the fold formed 
by the fusion of the dorsal surface of the basis capituli with the roof 
of the camerostome (see PI. Ill, fig. 7, o.Gen.org.). It occupies the 
entire width of the camerostome and, on account of its somewhat 
prominent and slightly everted lips, is readily seen when the capitulum 
is sufficiently depressed to expose the lower part of the camerostome. 
The Capitulum. 
Plate IV, figs. 8, 9, and 10; Plate V, figs. A-K ; 
Text-fig. 2. 
In common with all the Iccodoidea, the first and second pairs of 
appendages of Argas persicus, in conjunction with the buccal cavity 
and pharynx, have undergone an extreme degree of modification, 
forming a complex and remarkable structure which articulates with the 
anterior portion of the prosoma. The complete arrangement is termed 
the capitulum. 
In spite of the alteration, due to this specialization, a homological 
comparison, of the various parts of which the capitulum is composed, 
with the coi’responding parts of the typical Arachnida, is not a matter 
of great difficulty h 
1 See Joiirdain, S. (1901), and Bonnet, A. (1907). 
