Annals of tile Transvaal Museum. 
75 
(except those of the first pair), show a false articulation at a distance from 
their proximal ends, equal to their diameters ; the coxae are contiguous, 
or almost so ; the tarsi are not provided with pulvilli. The integument is 
of a colour varying from dirty yellow to dark brown ; there are no 
chitinous plates, either as dorsal shield or ventral or anal plates ; the 
integument instead is adorned with pits, furrows, and sculptures of various 
forms. The stigma tic plates are situated between the last two pairs of 
legs, laterally and dorsally of the coxae. The sexual pore is ventral, median, 
transverse, and situated opposite the intervals between the first two pairs 
of legs ; in the male the pore is narrow, almost as long as wide, and semi- 
lunate ; in the female the pore is an elongate slit almost as wide as the 
rostrum, with its edges parallel ; otherwise the two sexes are almost 
indistinguishable : from each other, except that in general the males are 
considerably smaller than the females, and do not distend to such an 
extent after feeding. The nymphs are very similar to the adults, except 
in lacking the sexual openings. 
The members of this family are parasitic on mammals, but especially 
on birds. There are two genera. Arc/ as, the fowl and bird ticks, and 
Ornithodoros, the tampans and sand ticks. 
Adults and Nymphs. 
A. Body usually flat, and thin at the edges ; no deep furrows on the 
ventral surface ; no eyes . . . . . . . . . . Avgas. 
AA. Body thick at the. edges ventral furrows present ; eyes present 
or absent . . . . . . . . . . . . Ornithodoros. 
Larvae. 
A. Body thin ; larvae active . . . . . . . . . . Argas. 
A A. Body thick and swollen larvae not active, or only so for a short 
time, at least they never feed . . . . . . Ornithodoros. 
Genus ARGAS, LATREILLE. 
Argus, Latreille (1796). 
Rliyncho prion, Hermann (1804). 
Argas, Latreille (Neumann, 1896). 
Body flat ; general contour usually oval with rounded extremities, 
sometimes orbicular, the anterior extremity narrower than the posterior, 
widest behind the fourth pair of coxae. Anterior end of the body projects 
beyond the capitulum like a hood. Lateral edges thin or a little thickened. 
Integument without papillae, but somewhat roughened by irregular zigzag 
wrinkles or folds, which are absent only at certain points, occupied by 
nearly circular pits ; these are shallow, more or less numerous and 
scattered, the larger ones form radiating series on both dorsal and ventral 
surfaces, of which the median posterior row is longest. Eyes absent. 
This genus includes the fowl tick and bat tick. They are easily 
recognised by their flattened bodies, which cause them to look not unlike 
bed-bugs. The edges of the body are very thin, and formed by a series 
of folds or rectangular plates. On both upper and lower surfaces there 
is a system of shallow shiny pits, with raised edges, grouped into lines 
radiating from a central point. 
