OCR Text |
Show 1885.] DR. ST. G. MIVART ON THE ARCTOIDEA. 341 more truly cylindrical, and longer than in other Carnivora. In the Dogs there is no trace of the anterior descending process of the temporal bone, which in the Mustelas confines the condyle of the lower jaw; in other Carnivora there is always a slight trace of the process, but in none does it enclose the condyles, as in most of the Mustelida. "The genera contained in this family are Mustela, Zorilla, Galictis, Bell (which must not be confounded with the Galictis of Is. Geoffroy St. Hilaire, published in the ' Comptes Rendus' for October 1837, p. 581), Mellivora, Ursitaxus, Helictis, and Gulo, in which the true molar of the upper jaw is transverse; Lutra and Mephitis, in which the tooth approaches more or less to a square form; Taxidea, in which it is triangular ; and, lastly, Meles, Arctonyx, and Mydaus, in which the true molar is longer than broad. " In the Ursida there are two well-developed true molars on either side of each jaw ; the ' carnassiere' * here has changed its functions, not being suited, as in other Carnivora, to cutting flesh, The palate is consider-ably elongated. In the Bears (Ursus and its subgenera) it is small, being robbed as it were of its nutriment by the true molars, which are very large. In the other Ursida (Pro-cyon, Nasua, Cercoleptes, Arctictis2, and Ailurus), the ' carnassiere,' especially that of the upper jaw, and the true molars are nearly equal in size, and also nearly resemble each other in other respects. 3 " In the true Bears the form of the lower jaw differs from that of any of the preceding Carnivora in having a projecting process on the underside of the ramus, and situated a little in advance of the angle of the jaw. The same character is also found in many Seals, which in several other respects appear to approach the Bears." 4 Mr. Waterhouse's two families Mustelida and Ursida were united by the late Mr. H. N. Turner 5 into the single family Ursidce, which was equivalent to the group here designated Arctoidea, and which he divided into the four subordinate groups (I) Ursina, (2) Ailu-rina, (3) Procyonina, and (4) Mustelina. As to these groups, Mr. Turner has expressed the following views, and made the following observations:- " In the Ursina we find no trace of a pterygoid fossa, the outer pterygoid process being closely pressed against the inner one, or true pterygoid bone, and sending off a strong lamina of bone to 1 The " carnassiere" is the sectorial tooth, i. e. the fourth uppsr premolar, against which the lower sectorial, or first lower true molar, bites. 2 That Arctictis is not an Arctoid but an ,Eluroid is now universally known and admitted, though D e Blainville figures it amongst the members of his genus " Subursus." 3 Mr. Waterhouse adds in a note:-" From an examination of the extsrnal characters of Bassaris astuta, it appears to m e that it belongs to this group," i. e. to the Ursida. 4 I have thought it worth while to reprint this extract, as being of so old a date as to have a certain historical interest, and because many Fellows of the Society may not possess the ' Proceedings' of so many years ago. 5 P*. Z. S. 1848, pp. 75-86. PROC. ZOOL. Soc-1885, No. XXIII. 23 |