304 
festoons are more marked in males, and the male often 
has tarsal spurs when they are absent in the female. 
(3) The females, on the other hand, may have 
porose areas, structures not found in the larva, nymph, 
or male (Figs. 95 and 96). The females alone become 
gorged in the manner so characteristic of the Ixodinae. 
Argasinae 
The head rises from the ventral surface, and the 
animalfis completely devoid of any scutum. The 
stigmata are situated between the third and fourth 
legs. The limbs, even in fully-grown and gorged 
animals, are large and strong in proportion to the body. 
The pulvilli of the tarsi are absent in the adult. 
The palpi are free, short, filiform, and consist of four 
segments. The eyes are absent in Argas , and may be 
present or absent in Ornithodoros . There is a hood-like 
fold (the camerostome) in Ornithodoros , lying in front 
of and around the base of the head (Fig. 100). This is 
not present in Argas. The abdomen does not become 
hypertrophied during feeding, as in most of the 
Ixodinae , out of all proportion to the head and limbs, 
and growth takes place uniformly ; the fully developed 
animals being identical, in all except size, with the 
smallest forms. 
Distinction of Sexes 
The males are with difficulty distinguishable from 
the females. In the male the genital opening is 
narrow and semilunar, nearly as long as broad. In the 
female the opening is an elongated slit with parallel 
lips, about as broad as the rostrum. 
