| OCR Text |
Show 1869.] CLASSIFICATION OF THE CARNIVORA. 11 In the singular genus Ailurus the auditory bulla is very small and simple, prominent and rounded on the inner side, with a very prolonged bony floor to the external auditory meatus. The carotid canal is large and distinct, rather behind the middle of the inner edge of the bulla. Paroccipital process long and trigonal, standing backwards and outwards, quite unconnected with the bulla, curved inwards at the extremity in old animals. The condyloid foramen is distinct in a flat exposed surface between tbe paroccipital and condyle. There is a well-developed rounded mastoid process, quite distinct from the paroccipital. The glenoid foramen is large, situated between the inner end of the tympanic meatus and the most prominent part of the large postglenoid process. There is a distinct alisphenoid canal. To pass to the Mustelidee :-Lutra is extremely Ursine in the base of its skull, although all the bones (including the auditory bulla) are remarkably thinned-out and flattened. The meatus is much prolonged. The carotid foramen is placed rather nearer the anterior than the posterior part of the inner edge of the bulla. The glenoid foramen is very distinct. The cavity of the auditory bulla (as is the case with many of the Mustelidee) is divided into several freely intercommunicating cells by thin incomplete bony septa placed transversely across the floor of the bulla, and connected at their outer end with the tympanic ring. The paroccipital process is greatly compressed from before backwards. The mastoids are prominent laterally. The foramen lacerum posticum very large. There is no alisphenoid canal. Enhydris differs from Lutra chiefly in the large size and more posterior position of the carotid foramen, and the very small size of the glenoid foramen. Meles presents, in the most characteristic manner, the form of auditory bulla assigned by Mr. Turner to this group, " rising suddenly on its inner side, and flattened off towards the meatus." Internally it has two transverse imperfect septa rising from the floor. The meatus is considerably prolonged. The paroccipital and mastoid processes are very well developed and far apart, the former rather compressed and pointed, the latter tuberous. The carotid foramen is placed rather behind the middle of the bulla. The condyloid foramen is small, its hinder border partially overlapped by a slight ridge of bone passing from the paroccipital process to the condyle ; but it is quite superficial and distinct from the foramen lacerum posticum. The glenoid foramen is distinct, though not very large. There is no alisphenoid canal. Taxidea differs from Meles in the remarkably inflated condition of the auditory bulla. Essentially, however, its characters are much the same ; the bulla is not so dilated at its hinder part as to come into contact with the paroccipital process, though in front it reaches to such an extent as to overlap and obscure the glenoid foramen. It has several partial transverse septa. In Mephitis, on the other hand, this region of the skull is nearly as much expanded and flattened as in the Otters. The bulla forms a very small prominence. The paroccipital process is widely separated |
