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Show 364 DR. ST. G. MIVART ON THE ARCTOIDEA. [Apr. 21, the external characters of this well-known genus1, comprising its three or four species, all exclusively Paleearctic. As to the skeleton, there are 14 or 15 dorsal, 5 lumbar, 3 sacral, and about 18 caudal vertebrae. The dorsal region I have found to be longer relatively than that of any other Carnivore, being most nearly approached by that of Ictonyx and Conepatus. To the cranial characters already given by Prof. Flower2, it may be noted, in addition, that the development of the sagittal ridge very much approaches that of Ailuropus. The infraorbital foramen is as large as in Ailurus. The postorbital processes are small as always hitherto, except in Bassaris and Bassaricyon. The palate extends as much behind the molars as in Procyon, but is narrower there than in Nasua. The pre-and postglenoid processes are so developed as to hold the mandible in their grasp. The frontal sinuses produce a prominence on the cranium; and the ethmoid is much more voluminous than in the previously noted form, and is even more voluminous than in Canis, though not so prolonged. The premaxilla does not attain the frontal. The transverse processes of the lumbar vertebrae are little developed, much as in Ailurus; but there are very large hyperapophyses on the laminae of the cervical vertebrae. The scapula is very nearly a right-angled parallelogram approaching a square. The ridges and condyles of the humerus are much produced, more so than in Nasua; and the metacarpals are stouter than in any form yet noticed. Molar formula = P. \, M . \. The first upper and lower premolar, however, are quite minute and often fall away. The molars differ from those of any iEluroid, Cynoid, or Arctoid yet described in the great preponderance in size of the first upper molars over the fourth premolars, both above and below. The first two upper premolars are much like the same teeth in Procyon and Nasua. The fourth is rather more sectorial than in those two genera, because there is only one internal prominence made of two very small internal cusps, with one developed from the internal cingulum as in the third upper premolar of Ailurus, only much less developed and distinct, so that they soon wear down into what is apparently the one prominence just spoken of. Of the three external cusps, the middle one greatly preponderates. This tooth has a superficial resemblance to the same tooth in Paradoxurus, Herpestes, and especially Bassaris. The first upper molar is different from any tooth of any other Carnivore, but most resembles the same tooth of Ailuropus. It has two equal-sized external cusps in front, with two small external cusps behind. One large (especially long) internal cusp, obscurely 1 I may be permitted to mention that I found the palmar surface naked; but the back of the tarsus was hairy, and naked surface narrow backwards to an acute termination. 2 P. Z. S, 1869, p. 11. |