Zoological Society. 409 



characters point out, than in many other orders ; but at the same 

 time, the general similarity of structure, to which I have before 

 alluded, pervading the different modifications of form, has rendered 

 it more than usually difficult to find characters truly essential, and 

 independent of adaptive differences, on which to found truly natural 

 subdivisions. These characters, when found in such an order ss the 

 Carnivora, we may fairly presuppose to be minute, and such of them 

 as I have been able to discover, and which I have found to be con- 

 stant so far as my opportunities of observation have extended, it is 

 my object here to point out ; with regard to the foramina, there is 

 one which seems to be very characteristic of the order itself, since 

 even in the true Bears, in which it does not exist as a canal, it is 

 represented by a very well-marked groove. In other Carnivora it 

 consists of a canal situated on the inner surface of the exoccipital 

 bone usually running from before backwards and downwards ; it 

 gives passage to a vein ; and if a special name should at any time be 

 deemed requisite, perhaps that of exoccipital canal may be found 

 suitable. The characters of which I purpose to make more or less 

 use in the subdivision of the order, are the structure of the ptery- 

 goid bones and processes, the presence or absence of the ali-sphenoid 

 canal, the form of the auditory bulla, and the course of the internal 

 carotid artery through its canal, the structure of the mastoid and 

 paroccipital processes, the situation of the foramen condyloideum, 

 and to some extent, the structure of the lower jaw. It is by the 

 fortunate circumstance of possessing in m)' own collection, crania 

 representing all the leading divisions of the order, that I have been 

 enabled, in the first instance, to remark the differences presented by 

 the characters alluded to ; but excepting a few genera, which I have 

 been enabled to examine in the museums of the College of Surgeons 

 and of this Society, it is only in the excellent series of skulls con- 

 tained in our National Museum that I have been able to collect 

 evidences of their constancjr. Such being the limits of my oppor- 

 tunities of observation, it cannot be expected that I should give 

 an opinion as to the precise zoological station of every one of the 

 numerous genera ; I will therefore take as a standard system the 

 classification made use of in the List of Mammalia published by 

 Mr. Gray, by order of the Trustees, since in the principal divisions 

 it accords pretty nearly with my own ideas ; simply pointing out 

 where I find any genus whose cranium I have examined which I 

 think requires to be altered in its position, and at the same time 

 assigning to the divisions characters of my own, and expressing my 

 opinion as to their rank. 



Although in that classification the Bears are placed near the ter- 

 mination of the series, yet I believe it to be most usual to reverse 

 the order and to begin with them ; therefore I will first point out 

 the characters which they present, and in so doing will confine 

 myself to the genus Ursus, the subfamily Ursina of Mr. Gray. We 

 here 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 enclose the ali-sphenoid 



