56 SUPPLEMENT ON 



ethmoidal (No. 3), the other beneath the vomer (No. 16). The 

 externa] part of the cranium usually terminates at the back of 

 its occiput into five points, sometimes prolonged into crests ; 

 that in the middle is single, and named medial, and is con- 

 nected by the cervical ligament with the spinous epiphysis 

 of the dorsal vertebrae ; the second are a pair, the intermedial ; 

 the third also a pair, are the external, and belong to the 

 mastoidean (No. 12), beneath which, in a channel formed 

 under the mastoidean and frontal, the temporal and palatine 

 apparatus is articulated. 



At the back of the encephalic box a sinus opens, which is 

 entirely surrounded by the occipital laterals, and forms the 

 posterior fossa. Between the orbitary alas, the frontals and 

 the bifurcation of the anterior sphenoid, there is a space 

 which forms the opening of the anterior fossa, usually entirely 

 membranous. The medial fossa is limited forward by a 

 transverse process of the orbitary ala, and behind by another 

 which extends over the internal face of the great ala and 

 posterior frontal. The two uniting behind and at the bottom 

 of this, there is in general a hole leading to a canal, which 

 terminates in the form of a funnel in the basilary, and lodges 

 the pituitary gland. 



Between the medial and posterior fossa? are the cavities of 

 the ear, consisting of two great hollows beneath the cavity 

 of the brain, and of divers depressions occupying the lateral 

 posterior angle of the cranium. The cranium has besides 

 some openings or cavities, which, in the recent state, are 

 generally closed by cartilages or by membranes. 



The upper jaw. Salmon and trout offer the clearest exam- 

 ples of the intermaxillary and maxillary bones. In acan- 

 thopterygians the intermaxillary (No. 17), forms nearly the 

 whole of the border of the upper jaw, and is moved by an 

 ascending apophysis, which slides before the anterior extre- 

 mity of the cranium. The maxillary (No. IS), is parallel to 



