94 Proceedings of the Royal Physical Society. 



superior connections of the vomer in the horse are peculiar, 

 inasmuch as the inferior surface of the leaflets of the ethmoid, 

 instead of lying in contact, as is usual, with the ethmo-vomerine 

 lamina for a considerable extent, is completely floored in by 

 the upper part of the palate bone, which is expanded for that 

 purpose. Even in the horse, however, a slender lamina, im- 

 mediately in front of the palate bone, and in contact with its 

 nasal foramen, passes downwards and inwards on each side 

 from the framework of the ethmoidal turbinations to the mar- 

 gin of the vomer; but the vomer and it are not anchylosed 

 until other sutures also have begun to be obliterated, 



The vomer in the rodentia is remarkable in having very 

 little tendency to come in contact with the superior maxilla- 

 ries. As far as I have observed, it is always continuous with 

 the lateral masses of the ethmoid. 



In the skull of the rabbit there is only one great anterior 

 palatine foramen ; for, although the mesial processes of the 

 intermaxillaries project well backwards, the palate plates of 

 the superior maxillaries do not come far enough forwards to 

 meet them. The vomer does not at all approach the superior 

 maxillaries; its posterior margin terminates inferiorly in a 

 thickened angle, which articulates with the intermaxillaries in 

 such a manner as to make their inferior aspect continuous with 

 the posterior margin of the vomer. In front of this, the laminae 

 bounding its groove are prolonged on the upper surface of the 

 intermaxillaries, as we have seen in other animals (fig. 4). 



In the porcupine and squirrel the vomer is not in contact 

 with the superior maxillary bones ; in the rat and the beaver 

 it is. 



In the quadrumana the mesial process of the intermaxil- 

 laries is so slightly developed that the anterior extremity of 

 the vomer frequently falls short of it by a slight interval. In 

 monkeys the vomer and orbital plates of the ethmoid are con- 

 tinuous ; but in the skull of a young Chimpanzee in the Uni- 

 versity Museum, the arch of bone which unites them is sepa- 

 rated at one extremity from the ethmoid by a suture, and at 

 the other only touches the vomer. This piece of bone has all 

 the essential characters of the sphenoidal spongy bones of the 

 human subject. 



