2 Rhipicephalus 
of the precise position of the lateral angle is sure to be obtained unless 
the capitulum is placed in an accurately horizontal position for ex¬ 
amination. 
Certain structures which are of great specific importance in other 
genera are practically identical in all species of Rhipicephalus. The 
dentition of the hypostome is always 3 | 3, and the coxal armature is so 
uniform that but slight assistance is to be expected from the study of 
it. A useful point, however, is the absence or presence of an anterior 
projection on coxa I, visible dorsally. This readily strikes the eye, is 
subject to comparatively little variation within the species, and at once 
relegates the specimen, at all events if a male, to a particular group of 
species. 
With very few exceptions the genus is inornate, so that a specific 
character of great utility in Amblyovima, Aponomma and Dermacentor 
is here practically lacking. The yellow legs of R. evertsi Neumann, 
1897, are noticeable, and some species have, as a rule, exceptionally 
dark scuta, but coloration on the whole—especially in specimens pre¬ 
served in spirit—is a doubtfully useful specific character. 
R. oculatus Neumann, 1901 and R. evertsi Neumann, 1897 are 
clearly separated from all other known species of Rhipicephalus by 
their hemispherical bead-like eyes. In a few other species the eyes 
are slightly prominent, but usually they are almost flat. Their com¬ 
parative size is of some importance, and, to a less extent, their colour. 
The size and shape of the spiracle, though by no means invariable, 
will often be found useful in diagnosing a species; the shape differs 
with the sex, that of the male always being the more elongate and 
comma-shaped. In some species the spiracle of the male narrows but 
slightly towards its termination, while in others {e.g. R. sanguineus 
Latreille, 1804) the tail of the comma is well-marked. There is usually 
present a more or less marked infolding of the spiracle rim on its 
dorsal border, but this “ rim-fold ” as we may call it is too variable to 
be of great assistance. It is often stated in the original descriptions of 
species of Rhipicephalus that “ the scutum of the male covers the whole 
dorsum,” or that this is not the case, the body extending beyond the 
boundary of the scutum; and in the same way the presence or absence 
of a caudal appendage is frequently given as a specific characteristic. 
As a rule it is merely a question of an unfed or of a distended 
male, and though distended examples certainly appear to occur more 
commonly in some species than in others, and caudal appendages Avhen 
present to be more pronounced, it would be exceedingly unsafe to say 
