Annals of the Transvaal Museum. 
93 
Tlie name Ixodes has served to describe the greater part of the 
Ixodinae of various countries and hosts. Although Koch gave a 
restrictive diagnosis, yet the inexperienced authors continued to 
include the most varied forms in this genus ; most of the descriptions 
were incomplete, insufficient, and their identification usually 
impossible. Koch himself has added to the confusion by giving the 
rank of species to forms, which differ only in age, or stage of 
engorgement, shape or size, secondary points in a question of this 
sort. 
The genus is sub-divided into three sub-genera — Euixodes, 
Ceratixodes and Eschatocephalus . These were formerly considered as 
three distinct genera, but Neumann considers that the characters 
which distinguished Ceratixodes and Eschatocephalus from Ixodes 
were not of sufficient importance to justify this distinction, therefore 
he included them in the genus Ixodes. 
The three sub-genera are characterised as follow : — 
Euixodes. Palpi long, valvate ; no eyes, anal groove may be 
open or closed behind ; in the male one pregenital, one genito-anal, 
two epimeral, one anal, and two adanal plates; stigmatic plates oval 
in male, circular in females. 
Ceratixodes. Palpi long, convex inside, and with a conical pro- 
longation in the male, and swollen at the end in the female. No 
eyes. Anal groove absent in female, but present in male. One anal 
and two adanal shields in the male ; stigmatic plates circular in both 
sexes. 
Escliatoceplialus. Palpi long, claviform, and flat in the female, 
piriform and not valvate in the male ; anal groove contouring anus 
in front and open behind. Stigmatic plates circular in both sexes. 
Irregular chitinous thickenings both above and below in the male. 
Stigmatic plates circular in both sexes. 
So far only three forms of Ixodes are known in South Africa. 
Ixodes pilosus occurs in the Cape Colony and Orange Kiver Colony, 
while its variety, Ixodes pilosus howaxdi, is found in the Transvaal 
and Natal. Ixodes rubicundus is reported and described by Neumann 
from specimens taken in Cape Colony. 
Males. 
A. Anal shield horseshoe shaped. 
B. Male large, 3.15 mm. long by 1.6 mm. wide; teeth on 
hypostome in one marginal row, other rows represented 
by crennlations ... ... ... ... ... pilosus. 
BB . Male small, 2.3 mm. long by 1.2 mm. wide; teeth on 
hypostome in three or four rows ... pilosus howardi. 
AA. Anal shield rectangular; sides parallel, longer than wide. 
rubicundus. 
