OCR Text |
Show IS MR. W. H. FLOWER ON THE [Jail. 14, inner side of the bulla, where it was so conspicuous in most of the Arctoidea, but it is represented hy a minute groove (car) deep in the recess of the foramen lacerum posticum. In the smaller members of the genus this groove is more superficial, but always very minute, and apparently never converted into an actual foramen except by the contiguous wall of the basioccipital. The paroccipital process (p) is flattened out over the back of the bulla, being applied closely to the whole of its prominent rounded hinder end, and projecting, as a rough tubercle, slightly beyond it. From the inner side of this process a strong sharp ridge runs towards the occipital condyle. This forms the posterior boundary of a deep fossa, at the bottom of which is the foramen lacerum posticum (I), and in the hinder part of which, under cover of the aforesaid ridge, the foramen condyloideum (c) opens. The mastoid process (m) is a moderately conspicuous rough prominence, not very widely separated from the paroccipital. There is no distinct glenoid fossa, nor is there an alisphenoid canal. This description applies equally well to all the true cats (genus Felis), including the slightly aberrant Cheetah, but not to any other members of the Order. I pass next to the Viverridce. In the African Civet (Viverra civetta) (fig. 7, p. 19) the auditory bulla is very prominent, smooth and oval, broader behind than before. The meatus has scarcely any inferior lip, its orifice (am) being close to the tympanic ring. The part of the bulla immediately surrounding the meatus is separated by a distinct groove from the much larger, more inflated, and more transparent inner, or, rather, posterior part, as it is in this animal. There is a septum within, disposed exactly as in Felis, but very short, owing to the small space it has to fill up, occasioned by the slight dilatation of the outer chamber. It is applied closely to the petrosal above, leaving a mere linear fissure, probably closed in the living animal, expanded at one end into a small triangular space, situated just over the fenestra rotunda. Instead of a carotid canal, there is a groove (car) on the inner side of the bulla, near its anterior end. The paroccipital (p) is triangular, spread very evenly over the hinder part of the bulla, applied to it " like the capsule of the acorn to the seed"*, and projecting slightly beyond it, as a rough pointed process. The ridge running from its inner side bounds the common fossa into which the condyloid foramen (c) and the foramen lacerum posticum (I) open. The mastoid process can be scarcely said to exist. An extremely minute aperture near the hinder end of the postglenoid process may represent the glenoid foramen. There is a distinct alisphenoid canal (a). In the Rasse (Viverra malaccensis) the bulla is large, as wide in front as behind, much elongated, narrow, and compressed laterally, corresponding, in fact, with the proportions of the entire cranium! Otherwise its structure is essentially the same as that of the Civet! * Owen, Cat. Osteological Series in Mus. Roy. Coll. Surg. vol. ii. p. 680. |