60 THE AMERICAN BEAVER. 



crosses the suture, and is lost in the intermaxillary. 

 The ante-orbital foramen is concealed from lateral 

 view by the most prominent part of this ridge. The 

 s. maxillary forms part of the orbit anteriorly. The 

 alveolar part of this bone is more prominent on the 

 outer surface — posteriorly it is supported by the 

 pterygoid bone, and the triangular palatal bone enters 

 as a wedge from behind as far as between the second 

 and third molars. The outer alveolar surflice has a 

 sharp slope toward the middle portion of the skull, 

 where it joins the perforated body of the pre-sphenoid. 

 In young subjiacts, before dentition is complete, the 

 upper alveolar part is bulbous and prominent In the 

 orbit the maxillary touches the frontal. The palatal 

 bone is somewhat cribriform — a ridge, commencing 

 with a point of bone, extends from its base, and is 

 continued along the maxillary, forming the posterior 

 half of the septum of the incisive foramina. The pos- 

 terior naris is nearly circular — the ascending portion 

 of the palatal supports above the two sphenoid bodies. 



The sphenoid bones are distinct, and about equal 

 in length. The outer pterygoid process is short, 

 strong, and divergent — the inner is long, and curves 

 backward so as to touch a process of the tympanic 

 bone, forming thus an oval lateral opening. Where 

 the sphenoidal bodies join, by their side, is the large 

 sphenoidal fissure, corresponding to the oval and 

 round foramina — the small optic foramen is seen by 

 the side of the pre-sphenoid. 



Brandt^ describes but one sphenoidal wing in the 



^ Memoires de I'Acaderaie Irapcriale des Sciences de Saint 

 Petersbourg. Sciences Naturelles, tome vii., 1855. Beitrage 

 zur natiern kentniss der gattung Castor, etc. J. F. Brandt. 



