XXIII] 



LACERTA VIVIPARA 



573 



Amphibia, converge under the base of the cranium towards the 

 middle line, and they articulate with outgrowths from the basi- 

 sphenoid, called basipterygoid processes. The palatines are united 

 in front with the floor of the nasal capsule: they bear on their 



prnac 



'+pto. 



FIG. 282. Diagram of the cranial roof in a Stegocephalan, various types of 

 Reptiles, and a Bird, showing modifications in the posterolateral region. 

 From Smith Woodward. 



A. Stegocephalan (Mastodonsaurus giganteus, about one-fifteenth nat. size, 

 after E. Fraas). B. Generalised Rhynchocephalan and Crocodilian. 



C. Generalised Lacertilian, often losing even the arcade here indicated. 



D. Generalised Bird. fr. Frontal. j. Jugal. {. Lateral temporal 

 fossa. la. Lachrymal, mx. Maxilla, n. Narial opening, na. Nasal. 

 o. Orbit, pa. Parietal, pmx. Premaxilla. prf. Prefrontal. ptf. Post- 

 frontal, pto. Postorbital. q.j. Quadratojugal. qu. Quadrate. . Supra- 

 temporal fossa. s.t. Supratemporals. sq. Squamosal. Vacuities 

 shaded with vertical lines, cartilage bones dotted. 



inner sides slight ridges which project somewhat into the cavity of 

 the mouth. These ridges support a pair of flaps of the lining of 

 the mouth, the palatal flaps, which as we have seen are charac- 

 teristic of all Amniota. In the lizard they remain unconnected 



