440 
Bioloyij lxo(}i(lae 
have fed) from the sheep of an infected herd. These ticks were 
placed upon an experimental animal which showed parasites in its 
blood and fever (40° C.) on the 10th day. It was found, as in the 
case of Haemaphysalis leachi and Piroplasma canis, that ticks 
descended from an infected mother were innocuous as larvae and 
nymphs but infective as adults. 
The ticks are stated by Motas to have been identified by 
Neumann, but Donitz (1905, pp. 107-109), has thrown doubt upon 
the correctness of the determination because in the collections of 
the Berlin Museum, ticks determined by Neumann as R. bursa, were 
found by him (Donitz) to be R. appendiculatus Nn., 1901. The 
error, as Donitz states, is probably explained by the circumstance 
that Neumann, at the time he identified the Berlin specimens, had 
not found the last-named species and consequently confused the 
two. Donitz (1907, p. 103), moreover, doubts the accuracy of Motas’ 
observation that R. bursa is a two-host tick. 
There is no doubt, however, that Motas experimented with 
R. bursa for he has sent me some of his specimens, and what is 
more, his observations on the biology of the tick, as far as they go, 
have been largely confirmed by me. It is clear that Donitz’s 
criticisms rendered it necessary to make a more detailed study 
of the subject.] 
Throughout the following experiments, R. bursa was raised upon the 
shorn scrotum of a ram, or the ear of a calf, the scrotum or ear being 
enclosed in a bag which was opened daily for inspection; the 
engorged ticks which had abandoned the host, were collected and 
enumerated. 
The time R. bursa remains upon the host. 
Larva-nymph. (First generation.) 
Larvae which emerged on 5. ix. 1911 from eggs laid by a $ received 
from Algeria, were placed on a ram 44-48 days after ecdysis, i.e. on 
three alternate days: 19-21-23. x. 1911. The 19th of October is 
reckoned as Day 1 in the following table. The ram was maintained at 
an average temperature of 9° C. 
