G. H. F. Nuttall 
53 
a host. During their long period of parasitism as nymphs they have 
doubtless undergone internal changes leading to maturity, otherwise 
they would not emerge so rapidly as adults from the nymphal skin. 
The adults, without further feeding, mate; the females oviposit in the 
chinks and crevices, and the larvae which emerge from the eggs await 
the coming of a host. Hooker, to whom we are indebted for most of 
what is known of this curious life-history, very naturally regards the 
habits of this tick as correlated with its peculiar form of parasitism in 
the ears of its hosts. He does not, however, discuss the subject. 
Animals rubbing their ears or heads against infested posts or trees 
(“rubbing places”) would necessarily pick up the waiting larvae. 
I would add that the structure of the mouth-parts, and especially 
the presence of an unarmed hypostome in the adults, indicate that 
they can scarcely be blood-suckers. It would be a matter of consider¬ 
able interest, it seems to me, to examine the internal anatomy of the 
adults of this species to see in how far it is modified, especially with 
regard to the pharyngeal pump, salivary glands and digestive organs. 
The life-history of 0. megnini is that of an animal highly specialized 
to a life of parasitism chiefly in the ears of its hosts. The larvae issue 
from eggs laid on rubbing posts or trees, and the like, some feet above 
the surface of the ground, so that they may readily gain access to the 
heads of their hosts. The larvae enter the ear unperceived. It would 
be a matter of increasing difficulty for succeeding stages to “cast anchor 
in such a small harbour” a second time for, apart from their increasing 
size, which would militate against their re-entering the ear, the number 
of ticks of later stages which survive even from a large batch of larvae 
(in all species of ticks) is very small and grows progressively smaller 
toward the period when maturity is reached. The tick, having entered 
the ear where it is safe for an unlimited time, takes advantage of the 
protection afforded and only leaves it once when it abandons it as 
a large nymph almost I’eady to cast its skin and emerge as an adult. 
The period of parasitism as a larva is normal, but that of the nymphal 
stages inordinately prolonged so that the tick only needs to go in and 
out once through the small aperture of the ear. It is owing to the 
choice of the ear for its place of feeding upon the host that the life- 
history of this tick has become so peculiarly modified. Its spiny 
integument, to whom it owes its name of “ spinose ear tick,” may be 
of use in connexion with its parasitism in the ear in lessening its 
chances of adhering with a large body-surface to the cerumen within 
the ear. 
