BY R. BROOM. 
481 
There is one interesting group of mammals — the Cheiroptera — 
in which the condition of parts has not, I think, been very care- 
fully observed, and from which we find considerable assistance in 
the solution of the present problem. In the insectivorous bat 
common in this district (Miniopterus Schreibersii, Natt.) the 
organ of Jacobson is well developed, but is unlike that of the 
typical mammal in being unusually short compared with its 
breadth. The premaxillre are moderately well developed, though 
they do not quite meet in the middle line, but they do not 
possess even a trace of palatine process. The cartilages of 
Jacobson are supported on the inner side by a small median bone 
which is quite unconnected with either the premaxill?e in front 
or the vomer behind. It is situated immediately in front of the 
anterior end of the vomer and clearly belongs to the same class 
of bones as the vomer proper, though instead of being closely 
related to the septal cartilage, it supports the cartilages of J acobson 
throughout almost their whole length. In front where the 
capsules are moderately close together, a transverse section 
reveals two bony plates supporting them anchylosed in their 
lower halves. Posteriorly the capsules are considerably apart, 
and the bone is here found as a flat plate stretching from the one 
to the other. 
In the common Australian flying-fox (Pteropus poliocephalus, 
Tern.) the condition is very different, but peculiarly interesting. 
The premaxillae are as well developed as in the Carnivora, though 
they do not quite meet in the middle line. The organ of Jacob- 
son as apparently in most insectivorous bats is here entirely 
absent, though the recurrent cartilages are fairly well developed 
as a pair of almost vertical plates. There is, however, no distinct 
supporting bone as in Miniopterus, nor a trace of palatine processes 
from the premaxillaries; but, on the other hand, the vomer is 
well developed, and from it a process of bone passes forward into 
the region corresponding to that occupied by the palatine process 
in ordinary mammals, though, unlike the palatine process, it only 
supports the posterior part of the cartilage. Whether in the 
foetal condition this process is ever distinct, I have not had the 
opportunity of ascertaining. 
