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Show 1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 357 and strong, sharp-pointed and much curved. The palmar and plantar surfaces are naked. There are 14 dorsal, 6 lumbar, 3 sacral, and 26 caudal vertebrae. The dorsal region is relatively shorter, and the lumbar and tail longer than in any other Arctoid. It has the relatively shortest first lower true molar. There are small rudimentary clavicles. The inner condyles of the humerus may or may not be perforated \ To the characters already pointed out by Professor Flower2 may be added the conspicuousness of the stylo-mastoid foramen and the flattened, broadened-out condition of the basis cranii external to it. The palate is not prolonged as in Procyon and Nasua, behind the molars, a peculiar pointed process projecting backwards from its hinder edge behind each last molar. Strong postorbital processes project both from the frontals and the molars. The alisphenoid is widely separated from the parietal by the wide junction between the squamosal and the frontal. The palatine also joins the orbitosnhenoid. There is a very large infraorbital foramen. The palate is very slightly arched, with an anteroposterior convexity. The lachrymal foramen is placed very low in the orbit. The mandible differs greatly in shape from that of any other Carnivore, and much resembles that of the Lemuroid, Microrhynchus. The inferior margin of its horizontal ramus is concave ; the symphysis is very long, and the postero-inferior part of the mandible is greatly expanded, the angle projecting downwards as well as backwards. There is no subangular process. The coronoid process is much prolonged upwards, and may sometimes incline a little forwards rather than backwards. Comparing this most arboreal Arctoid with Arctictis, the most arboreal iEluroid, one is struck with the similarity which exists in the proportional length of the limbs, and in the presence of the chevron bones beneath the tail, of which there are here seven. The ultimate phalanges are more elongated and curved than in Procyon and Nasua; but there are no large bony plates to sheath the bases of the claws as in the Cats, nor have the penultimate phalanges the feline lateral excavation. Molar formula = P . §, M . |. The molars are very simple in structure, with low flat crowns, though essentially like those of the two preceding genera. The fourth upper premolar and first upper molar are formed on the same type as those of Procyon, but the cusps are much less developed. The second lower molar is rather smaller in comparison with the first one than is the case in Nasua and Procyon. The other lower molars are formed on the same type as those of the two last-mentioned genera, but are more flattened on the surface and less tuberculate. 1 Sir Richard Owen (in his Anat. of Vertebrates, vol. ii. p. 509) have seen the condyle notched in the right, and perforated in the left humerus." 2 P. Z. S. 1869, pp. 9, 10. P R O C ZOOL. Soc-1885, No. XXIV. 24 |
