THE MALAYAN RUSA-DEER. 189 
irregular form. Whether this was the effect of disease 
or of advancing age, or whether it arose solely from 
some temporary and accidental cause, will probably be 
determined by the growth of the present year, which is 
not yet sufficiently advanced to enable us to ascertain 
its probable form. 
With regard to the sub-orbital sinus, which in this 
and all the neighbouring species is of very considerable 
size, its uses are evidently connected with the function 
of respiration, and probably also with the sense of smell. 
It is denoted externally by a longitudinal fissure, placed 
beneath the inner angle of each of the eyes, and leading 
into a sac or cavity, which in some cases communicates 
internally with the nose; and its inner surface is lined 
by a membrane abundantly supplied with follicles for 
the secretion of mucus, which is sometimes produced 
in very large quantities. This latter circumstance has 
induced some naturalists to regard these openings as 
mere cuticular appendages. That they really, in some 
species at least, communicate with the nostrils, is proved 
by the observations of Mr. White of Selbourne, who 
states that in consequence of this communication the 
Fallow-Deer are enabled to take long-continued draughts 
with their noses deeply immersed in the water, the air 
in the mean time passing through the sub-orbital slits. 
So singular a statement was naturally enough doubted 
and called in question; but it has never, so far as we 
know, been impugned on ocular testimony ; while it has 
received the fullest confirmation from other observations 
made upon the very species now under consideration, in 
which the air passing from the sub-orbital sinus, while 
the animal drinks, may be felt by the hand, and even 
