On the value of the characters of the base of the cranium in the classification of the order Carnivora : and on the systematic position of Bassaris and other disputed forms / by William Henry Flower.

  • Flower, William Henry, 1831-1899.
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: On the value of the characters of the base of the cranium in the classification of the order Carnivora : and on the systematic position of Bassaris and other disputed forms / by William Henry Flower. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    D. 12, L. 6, S. 3, C. 22. Sucli a formula is perfectly exceptional, as no known Carnivore lias so few (lorso-lumbar vertebrae as 18. The skeleton in the Museum of the Royal College of Surgeons has C. 7, D. 13, L. 7, S. 3, C. 23 or more, the dorso-lumbar vertebrae being 20, the most usual number in the order. Although the pre- vailing number of the rib-bearing vertebrae of the Arctoid group is 14 or 15, and of the iEluroid and Cynoid 13, there are so many exceptions that this character cannot have much weight in deter- mining the position of any doubtful form*. The skull of Bassaris (fig. 3 a, p. 10) in its general form presents a nearer approach to that of Procyon than to any other known Carnivore, allowing for the considerable difference of size and conse- quent alteration in proportion of brain-case to surrounding parts. The general form of the brain-case, and the direction and develop- ment of the zygomatic arches, are exceedingly similar. The prin- cipal differences are, that in Bassaris the muzzle is narrower and more pointed in front, the orbits larger and more sharply defined from the temporal fossae by the larger postorbital processes, and especially that the bony palate is very much shorter, as it terminates at the level of the hinder border of the last molar tooth, while in the Raccoon it is continued as far as the anterior end of the pterygoid bones, or very nearly to the level of the anterior edge of the glenoid fossa. This distinction is of no more than generic importance, as similar variations in the extension of the palate backwards in the middle line are met with among different, and otherwise closely allied, members of the Viverridce and of the Mustelidce. The form of the lateral margins of the palate bones, of the pterygoids, and of the hinder margin of the palate itself is precisely the same in both Procyon and Bassaris. The mandible of Bassaris differs from that of Procyon only in having the coronoid process less recurved—a very common character in the mandibles of smaller species both of the Viverridce and Mus- telidce. In the special part of the skull which affords the most strongly marked distinctive characters between Procyon and the Vi- verridce, Bassaris agrees in every point with the former. The audi- tory bulla is almost a miniature representation of that of Procyon ; it is quite simple, without any septum, prominent at the middle part, but falling away before and behind, and prolonged externally into a well-developed bony meatus (am). The carotid foramen (car) is large, situated rather behind the middle of the inner border of the bulla. The paroccipital (p) and mastoid (m) processes, though more feebly developed than in Procyon (as is usually the case with smaller animals), have the same general characters, the former especially projecting outwards and backwards, quite free from the bulla. The condyloid foramen (c) is exposed on a flat surface, quite distinct from the foramen lacerum posticum (l). The glenoid * Among the other Procyonidai, Cercoleytes has 15, Procyon 14, and Nasua 13 pairs of ribs, though in eacli instance the numbers seein occasionally to vary in the same species, to judge by the discrepancy in the statements of different, authors. [31]