1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 355 



other Arctoid except Procyon, where it is still longer aad where the 

 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 process^ 

 is less prominent, the paroccipital process less prominent and more 

 applied to the bulla. The bulla is more inflated, the carotid fora- 

 men 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. j, M. |. 



The first premolar, both above and below, has two roots. Com- 

 pared 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 internal cingulum is obsolete.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 i.s also 

 as prominent as it is in Canis, Bassaris, Ailurus, Galictis, Ictonyx, or Helictis, 

 and it is more prominent than it is in Mydaus, Mtistela, or Putorms. On the 

 contrary, it is not so prominent in Nandinia as it is in Trocyon, Meles, Taxidea, 

 Arctonyx, Gulo, Mephitis, Conepatus, Mellivora, Lutra, or Enhydra. 



