1869. | CLASSIFICATION OF THE CARNIVORA, 15 
from the paroccipital to the condyle, it is never sunk into a common 
opening with the foramen lacerum posticum. 
7. The glenoid foramen is always present, and generally very con- 
spicuous. In Enhydris it is least so. 
8. The alisphenoid canal is present in the true Bears and Aiélurus, 
absent in all the others. Hence it cannot be used to characterize the 
entire group, though useful in aiding its subdivision. 
The group thus defined is, I think, too extensive, and presents too 
great variation among its members, in dentition and external cha- 
racters, to constitute a Family, as proposed by Mr. Turner. I 
would rather regard it as a primary section of the fissipedal Carni- 
vora, to which the name of ARcrorDEA might be given. 
I perfectly agree with Mr. Turner that it is further divisible into 
four chief sections, or families, as 1 should call them—the Urside, 
Ailuride, Procyonide, and the Mustelide. The further considera- 
tion of these divisions must be reserved for the present, my purpose 
now being to establish the group drctocdea upon a perfectly secure 
basis. 
I will now pass to a genus as far removed from the Bear in its 
general structure as it will be seen to be in the construction of the 
base of its skull, Felis. Figs. 5 and 6 (pp. 16 & 17) are taken from 
the Tiger (J’. tigris). 
The auditory bulla is very prominent, rounded and smooth on the 
surface, rather longer from before backwards than transversely, its 
greatest prominence being rather to the inner side of the centre. The 
lower lip of the external auditory meatus (a.m) is extremely short ; 
the meatus, in fact, looks like a large hole opening directly into the 
side of the bulla. On looking into this hole, at a very short distance 
(in fact, just beyond the tympanic ring) a wall of bone is seen, quite 
impeding the view or the passage of any instrument into the greater 
part of the bulla. On making a section (fig. 6), it will be seen that 
this wall is a septum (s) which rises from the floor of the bulla, along 
its outer side, and divides it almost completely into two distinct cham- 
bers ; one (0.c), outer and anterior, is the true tympanic chamber, and 
contains the tympanic ring, membrane, and ossicula, and has at its 
anterior extremity the opening of the Eustachian tube (¢) ; while the 
other (z.c), internal and posterior, is a simple but much larger cavity, 
having no aperture except a long but very narrow fissure (*) left 
between the hinder part of the top of the septum and the promon- 
tory of the petrosal, which fissure expands posteriorly, or rather at 
its outer end, into a triangular space, placed just over the fenestra 
rotunda or cochlearea (7), so that the opening of this fenestra is partly 
in the outer and partly in the inner chamber of the bulla. This 
chamber is formed by a simple capsule of very thin but dense bone, 
deficient only at a small oval space in the roof, where the petrosal 
projects into and fills up the gap, except such portion of it as is left 
to form the aperture of communication with the outer chamber. 
Not only are these two chambers thus distinct, but they are 
originally developed in a totally different manner. At birth the only 
ossification in the whole structure is the incomplete ring of bone sup- 
