162 ON THE MORPHOLOGICAL CONSTITUTION OF 



I have already directed attention as the combined ethmoidal 

 neurapophyseal elements. In the turtles the maxillaries meet 

 across the palatal vault in front of the united ethmoidal 

 neurapophyses, so that the latter are pushed backwards, and 

 are in contact laterally with the palatals in the vault of the 

 palate ; while in the tortoise the latter want entirely the 

 palatal processes, consisting, as Cuvier expressed it, only of 

 their upper portions, and extending outwards on each side from 

 the outer margins of the so-called " vomer," and of the ptery- 

 goids, to the inner margins of the maxillaries. Now, let the base 

 of the skull of a tortoise, a turtle, and a crocodile, be examined 

 side by side. In all three we shall find the intermaxillaries 

 in front. The maxillaries, although they do not meet across 

 the palate of the tortoise, do so in that of the turtle, and thus, 

 as in the crocodile, bound posteriorly the intermaxillary 

 segment of the palate. The transverse union of the maxillaries, 

 in the turtle and crocodile, pushes back the ethmoidal 

 neurapophyses (which are in contact with the intermaxillaries 

 in the tortoise), but to such an extent in the crocodile that 

 the ethmoidal neurapophyses, also themselves much elongated, 

 carry back the pterygoids, so that the latter almost entirely 

 conceal the post-sphenoidal centrum. The outer margins of 

 the pterygoids, already curved downwards in the tortoise and 

 turtle, pass downwards and inwards in the crocodile, so as to 

 meet again in the mesial line of the palatal vault. The bony 

 septum of the pterygo-ethmoidal portion of the nostrils of the 

 crocodile is at the same time seen to be the result of the 

 extension downwards in the mesial plane of the middle ridge 

 of the so-called " vomer " of the tortoise or turtle, and of the 

 connection of the anterior part of that double bone with the 

 ethmoidal neurapophyses. It will thus be observed, that if 

 the maxillaries of the tortoise were united across the palate, 

 in front of its ethmoidal neurapophyses, to a considerable 

 extent backwards ; if the ethmoidal neurapophyses were also 



