| OCR Text |
Show 1869.] CLASSIFICATION OF THE CARNIVORA. 13 gular, the mastoid process strong and rounded. The carotid foramen conspicuous, near the middle of the inner border of the bulla. The condyloid foramen not bounded posteriorly by a ridge. The glenoid foramen large, close to the anterior edge of the meatus externus. In Galera the bulla is less prominent, the carotid foramen partly concealed by the basioccipital. The glenoid foramen large, and rather more internally placed than in the last. In Maries the bulla is elongated from before backwards. The paroccipital and mastoid processes are small. The carotid foramen is partly concealed by the basioccipital. The condyloid foramen partially overhung .posteriorly by the ridge from the paroccipital. The glenoid foramen large, situated at the upper anterior angle of the auditory meatus. In Mustela the dilatation and elongation of the bulla is carried to a great extent. The meatus is directed much forwards, and appears externally to be very short; but this is occasioned (as shown in the transverse section, fig. 4) by its inferior lip being covered up by a thick layer of cancellous tissue, of which the whole parietes of the bulla are to a great extent composed, and which adds much to its external bulk. But for this peculiarity, the general form of the cavity is not unlike that of Ursus. In addition to this cancellous structure in the wall, a considerable portion of the interior, especially of the inner and lower parts, is pervaded by numerous fine osseous septa and trabeculae. The paroccipital and mastoid processes are very feebly developed, especially in the smallest members of the group, where they are flattened and lost on the expanded posterior end of the bulla. The carotid foramen is placed conspicuously at, or rather inffront of, the middle of the long straight inner wall of the bulla. The condyloid foramen is quite exposed, and distinct from the foramen lacerum. The glenoid foramen is tolerably large, and situated just in front of the external auditory meatus. As in the preceding genera, there is no alisphenoid canal. Fig. 4. Section through the auditory bulla of the Polecat (Mustela putorius). Twice the size of nature. (The letters as in fig. 2.) Pt. The petrosal. In Rhabdogale the form of the auditory bulla externally much resembles that of Mustela, though rather less inflated ; but a section shows that its walls want the peculiar cancellous structure noticed in |
