GENERAL CHARACTERS. 



903 



supraoccipital (OS), which, although double in the figured skull, is 

 usually a single bone, appears to be developed inferiorly from car- 

 tilage and superiorly from membrane ; it usually forms the upper 

 border of the foramen magnum, and is not unfrequently produced 

 posteriorly into a long spine. On the lateral aspect of the cranium 

 are placed the jugal (J), and quadratojugal ( QJ\ which connect 

 the quadrate with the maxilla; while inferiorly (fig. 825) we may 

 have a median splint-like parasphe?ioid (Ps), and always a single or 



Fig. 825. — Under or palatal view of the cranium represented in fig. 824. V, Vomer ; P, Pala- 

 tine ; Pt, Pterygoid ; QJ, Quadratojugal ; Ps, Parasphenoid. (After Fritsch.) 



paired vomer ( V), and the paired pterygoids (-Pt), and palatines (P). 

 The two latter, it may be observed, are developed upon the primi- 

 tive palatopterygoid bar ; while the parasphenoid, when present, 

 underlies the basicranial axis, and if largely developed, as in Teleos- 

 tean fishes and Amphibia (fig. 825), seems to take the place of 

 the basi- and presphenoid. 



In the cranium of which an upper view is given in fig. 824 the 

 whole of the region behind the orbits is completely roofed over by 

 bone, so that a secondary roof is thus formed above the roof of the 

 much smaller brain-case which lies within. In most Reptiles there 

 are, however, vacuities or fossae in this outer roof (as in fig. 826), 

 although in the Turtles and the Ichthyosaurs (fig. 1024) this roof 

 persists. In fig. 826 the upper-lateral vacuity is termed the supra- 

 temporal fossa, and is bounded below by the superior temporal (or 



vol. II. B 



