Zoological Society. 407 



conceal the vidian canals, and that the skull be sufficiently well- 

 cleaned, their anterior openings can usually be seen without difficulty. 

 I have succeeded in tracing it throughout the Carnivora, Ruminantia, 

 Pachydermata* and Edentata ; it is always, at least in its posterior 

 portion, wholly or partly enclosed by the true pterygoid bone, which 

 constitutes the inner wall of the pterygoid fossa, so that the term 

 " pterygoid canal," which has been applied to it in Human Anatomy 

 synonymously with that of " vidian," is very correctly applicable. 

 Its anterior opening is always just beneath that of the foramen 

 spheno-orbitarium, so that the issuing nerve can communicate 

 readily with the second branch of the fifth pair, soon after its exit 

 through the foramen rotundum. It may be further remarked, that 

 the opening of the true vidian canal is always on the inner side of 

 the foramen rotundum, while that of the ali-sphenoid canal is always 

 on its outside, and usually covers and conceals it. However, I 

 think I have removed all doubt by the dissection of a sheep's head, 

 in which I have traced the vidian nerve from its junction with that 

 of the seventh pair to the foramen in question ; the course of the 

 nerve is usually longer and more tortuous in the lower animals than 

 in Man. 



I have also perceived in some skulls belonging to the Marsupial 

 order, a canal which from its situation seems to be the vidian ; in 

 the Rodent order, a distinct vidian canal seems rendered needless 

 by the constant existence of a fissure communicating between the 

 posterior nares and the apex of the orbit, and in some skulls I can 

 even see faint indications of a groove extending from the foramen 

 lacerum anterius round the inner side of the base of the pterygoid 

 bone to the margin of the fissure ; but I would not at present ven- 

 ture to deny the existence of a vidian canal in any species, con- 

 sidering that, with the exception of some Edentata, as the Armadil- 

 loes, in which its calibre is proportionally very large, it is extremely 

 difficult to perceive in any small-sized animal. 



It now becomes my task to place in an intelligible light, the ob- 

 servations on the crania of the Carnivora, which have led me to 

 believe that the classification of this order may be set upon a firmer 

 basis than that afforded by the characters generally made use of. 

 In the course of the present disquisition, I must be allowed to con- 

 sider this order exclusively of the Insectivora and Marsupials, which 

 are by many naturalists included, the former indeed most usually, 

 as part of the order in question. When the order Carnivora is thus 

 circumscribed, we find it to consist of a very great number of species, 

 being exceeded in that respect among the Mammalian class only 

 by the Rodentia ; and notwithstanding the striking difference of ex- 



* 111 the justly celebrated work by Mr. Swan, on the Comparative Anatomy 

 of the Nervous System, it is said that the Common Hog does not possess a di- 

 stinct vidian nerve running in a bony canal ; and certainly, I have not very clearly 

 succeeded in demonstrating the canal in that species, but a skull in my collection 

 of the Sus Indiam shows it very well ; in the Babirussa, the anterior and posterior 

 portions of the canal each open into the sphenoidal sinus, which has great extent 

 in that animal. 



