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Show 1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 355 other Arctoid except Procyon, where it is still longer and where radius is at its maximum of relative length in that group. The length of the skull compared with that of the spine is greater than in any other Arctoid except Melursus, while the relative breadth of the skull behind the postorbital processes is at its maximum. When compared with the total length of the skull, the palate of Nasua is lower than in any other Arctoid except Procyon, and the length of the pelvic limb, compared to that of the pectoral one, only attains the same proportion in Lutra. As to the skull, the form of the auditory bulla and parts adjacent has been described by Professor Flower \ The muzzle is longer, and more upturned towards the apex than in the skull of Procyon; the frontal region also is more convex and swollen ; the mastoid process2 is less prominent, the paroccipital process less prominent and more applied to the bulla. The bulla is more inflated, the carotid foramen situated more forwards, and the condyloid foramen is smaller and less conspicuous. The palate is not only much prolonged behind the last molars, but remains very broad there. The maxilla forms, indeed, but a very small bony floor to the orbit. The mandible has no subangular process, and the angle is very small and less produced and pressed upwards than in Procyon. Sir Richard Owen remarks (Anat. of Vertebrates, vol. ii. p. 501) that in Nasua "the olfactory chamber, with the superior turbinals, extends above the whole rhinencephalic fossa, and forms in part the frontal elevation of the cranial contour." The ulna is much broader and less slender than in Procyon, and the fibula is more divaricated from the tibia. The pollex and hallux are also rather longer in proportion to the longest digits. Molar formula = P. f, M . §. The first premolar, both above and below, has two roots. Compared with the teeth of Procyon, those of Nasua have the following characters :-The fourth upper premolar has the postero-inner and principal outer cusps less developed. In the first upper molar, the internal cingulum is obsolete. The second upper molar is tricuspid instead of quadricuspid, the postero-internal cusp being generally obsolete. In the first lower true molar the antero-internal cusp may be wanting, and the postero-internal may be smaller than in Procyon. The second inferior molar may be without the fifth or median and hindmost cusp of the Raccoon. In the milk dentition, the first upper deciduous molar is a simple conical tooth. The second one is similar, save that it has a small posterior cusp. The third upper molar is unlike any other 1 Loc. cit. p. 9. . . 2 The mastoid process is almost, if not quite, as prominent in the ^luroid Nandinia (see P. Z. S. 1882, p. 170) as it is in Nasua. In Nandinia it is also as prominent as it is in Canis, Bassaris, Ailurus, Galictis, Ictonyx, or Helictis, and it is more prominent than it is in Mydaus, Mustela, or Putorius. O n the contrary it is not so prominent in Nandinia as it is in Procyon, Meles, Taxidea, Arctonyx, Gulo, Mephitis, Conepatus, Mellivora, Lutra, or Enhydra. |
