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Show 1869.] CLASSIFICATION OF THE CARNIVORA. 15 from the paroccipital to the condyle, it is never suuk into a common opening with the foramen lacerum posticum. 7. The glenoid foramen is always present, and generally very conspicuous. In Enhydris it is least so. 8. The alisphenoid canal is present in the true Bears and Ailurus, 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 characters, to constitute a Family, as proposed by Mr. Turner. I would rather regard it as a primary section of the fissipedal Carnivora, to which the name of A4RCTOIDEA 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 Ursidee, Ailuridce, Procyonidce, and the Mustelidee. The further consideration of these divisions must be reserved for the present, m y purpose now being to establish the group Arctoidea 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 (F. 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 chambers ; one (o.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 (e) ; while the other (i.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 promontory 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 (r), so that the opening ot 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 onlv 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- |