SKULL OP" THE CROCODILE. Ill 



nasals, 15, aud tlie lachrymal, 16, as well as with its fellow 

 of the opposite side of the arch. The smooth, expanded 

 horizontal plate, which effects the latter junction, is called 

 the palatal plate of the maxillary ; the thickened external 

 border, where this plate meets the external rough surface 

 of the bone, and which is perforated for the lodgment of 

 the teeth, is the " alveolar border" or " process" of the 

 maxillary. The haemal spine or key-bone of the arch, 22, 

 is bifid, and the arch is completed by the symphysial 

 junction of the two symmetrical halves ; these halves are 

 called " premaxillary bones:" these bones, like the maxil- 

 laries, have a rough facial plate, and a smooth palatal 

 plate, with the connecting alveolar border. The median 

 symphysis is perforated vertically through both plates ; 

 the outer or upper hole being the external nostril, the 

 under or palatal one being the prepalatal or naso-palatal 

 aperture. 



Both the palatine and the maxillary bones send outwards 

 and backwards parts or processes which diverge from the 

 line of the haemal arch, of which they are the chief ele- 

 ments ; and these parts give attachment to distinct bones 

 which form the " diverging appendages" of the arch, and 

 serve to attach it, as do the diverging appendages of the 

 thoracic haemal arches in the bird, to the succeeding arch. 



The appendage 24, called " pterygoid," effects a more 

 extensive attachment, and is peculiarly developed in the 

 crocodilia. As it extends backwards it expands, unites 

 with its fellow below the nasal canal, and encompassing 

 that canal, coalesces above it with the vomer, and is firmly 

 attached by suture to the presphenoid and basisphenoid : 

 it surrounds the hinder or palatal nostril, and, extending 

 outwards, it gives attachment to a second bone, 25, called 

 " ectopterygoid," which is firmly connected with the max- 



