4 
Rh ipic€2)h aim 
As regards the males, we have still to consider the dorsal sculpture. 
The cervical and lateral grooves are of importance, and there are usually 
present on the posterior portion of the scutum three furrows or pits 
which are fairly constant for the same species and which may be called 
the “ dorsal furrows.” 
The punctation of the scutum presents a great difficulty. There is 
certainly for each species a characteristic punctation very recognisable 
in typical examples, but often widely departed from in individuals, or in 
local varieties, and when this is the case the difference of facies between 
two ticks otherwise structurally identical may be very great. A striking 
case is the tick named by Neumann H. falcatus, a densely punctate 
form which at the first glance bears no resemblance at all to R. sivius, 
where the punctations are few, and arranged in linear series. Moreover 
R. falcatus typically possesses very characteristic anal plates quite unlike 
those we are accustomed to expect in R. simus, and there is no anterior 
promineuce on coxa I. Yet we can find no other structural points in 
which these forms differ, and moreover we possess a tube of ticks from 
Nyasaland which we have been quite unable, after repeated attempts, 
to sort out. There are many undoubted R. falcatus, a considerable 
number of obvious R. simus, and every intermediate grade of anal plate, 
prominence of coxa I, and punctation. 
If the males of Rliipicephalus are difficult to identify, the characters 
presented by the females are even more unsatisfactory, for not only are 
they without anal plates, but the shape of the basis capituli differs 
little in the various species, and the anterior prominence of coxa I is 
never noticeable. The shape of the scutum should be noted, the 
presence or absence of a lateral groove, and the scutal punctation. 
Further assistance will be received from a study of the porose areas and 
of the spiracles, but, as we have already said, a single female, unless it 
presents some unmistakeable peculiarity, is a very unsatisfactory basis 
for the formation of a new species. 
In identifying a male Rliipicephalus the best guides will be found to 
be, the anterior prominence on coxa I, the exact shape of the basis 
capituli carefully orientated, and the position and nature of the lateral 
angles (whether obtuse, acute, or about a right angle); the dorsal 
furrows ; the anal plates, the grooves and punctations of the scutum, 
and the spiracles. 
If the belief in the great specific variability of Rliipicephalus 
depended entirely on the study of ticks captured under ’natural con¬ 
ditions it might be argued that forms in reality distinct had been 
