74 
Annals of the Transvaal Museum. 
r 
The rostrum comprises (1) two mandibles , each formed of a shaft, 
the lover half of' which is swollen to receive the insertion of muscles, 
while tne upper half is flattened and narrow, terminated in front by a 
finger or digit, recurved in a hook at its tip: The base of the digit is 
wide and swollen; on its dorsal surface it bears two unequal apophyses, 
each with one or more processes and teeth, recurved, one of which is 
always terminal. These mandibles are wrapped throughout their full 
extent in a membranous sheath, a prolongation of which extends over the 
digit ; (2) a hypostome shaped like a dart, armed on its lower face with 
backward projecting teeth placed symmetrically on each, half ; (3) two 
palpi composed of four articles each. 
Respiration is by tracheal tubes opening to the exterior through two 
stigmata, surrounded by stigmatic plates, circular or lunate in outline, 
and situated near the fourth pair of coxae. 
Legs with six articles (seven or eight by the apparent division of one 
or two articles into two parts) ; coxae immovable ; tarsi provided with two 
claws, with or without a sucker-like disk called the ambulacre. The tarsus 
of the first pair bears on its dorsal edge, near the distal extremity, a cup- 
like depression, the organ of hearing known as “ Haller’s organ.” 
Larvae with six legs, without sexual orifice, and without large 
stigmatic plates ; respiration takes place through one to four pairs of small 
openings along the lateral edges. * 
Hympks with eight legs, and no sexual orifices ; two large stigmatic 
plates present. 
The members of the family live as parasites on mammals, birds, and 
land reptiles, the blood of which they suck by fixing their rostrum into 
the skin. The hypostome is provided with teeth, which, with the teeth 
of the mandibles, hold it in place. The palpi spread outward and apply 
themselves to the skin on each side, and at right angles to the point of 
piercing. The "Females leave the host to lay their eggs in some protected 
place on the ground, such as under a clod of earth, stones, or rubbish. 
The family Ixodidae is sub-divided into two distinct groups or sub- 
families, the Argasinae or fowl ticks, and tampans, and the Ixodinae or 
true ticks. 
A. Rostrum inferior, hidden under a. frontal projection of the body ; 
no anal plates ; no pulvilli at tips of tarsi . . . . Atgasinae. 
AA. Rostrum terminal at anterior end of body; a dorsal shield 
present ; tarsi with pulvilli . . . . . . . . Ixodinae. 
Sub-Family ARGASIHAE. 
Rostrum inferior (except in the larvae, when it is often terminal, or 
nearly so, and in the nymphs, when it is sub-terminal, part of it projecting 
beyond the anterior end of the body), that is, the rostrum is situated 
on the ventral surface of the anterior end of the body, which projects over 
if like a hood. The digit of the mandibles is irregularly triangular, wide 
and swollen at the base ; the inner apophysis is elongated, with the 
terminal tooth recurved outward, and the process more or less transverse, 
pointed at both extremities and inserted at about the middle of the length 
of the apophysis ; the outer apophysis is elongate, provided on its outer 
edge with two large teeth, similar in form and almost parallel. The palpi 
are free, elongate, and cylindrical ; the articles differing little from one 
another. The legs are a little unequal in length, the second pair is the 
shortest, the fourth pair the longest ; six articles, the third and the tarsi 
