MORPHOLOGY OF THE VERTEBRATE SKULL 13 
sented in the Cynodonts and that these in turn are homologous 
with the alisphenoids of crocodiles and Dinosaurs. Whence do 
these alisphenoids of reptiles and mammals arise? Were they 
derived through the transformation of basipterygoid processes 
such as are represented in the lizard (Gaupp)? Or were they 
derived through the transformation of the elements called 
epipterygoids in Sphenodon (Broom ’09)? 
Fig. 10 Brain case of a predentate dinosaur Saurolophus osborni (Barnum 
Brown, Bull. Am. Mus. Nat. Hist., vol. 31, 1912, p. 134, text-fig. 3). 
The alisphenoid (Al. sp.) articulates with the prootic; it lies in front of the prootic foramen (V) and 
chiefly behind the foramen for nerves IJ, III, IV. Pr.sp., orbito-sphenoid. 
In the palatal aspect (fig. 11) of the skull of Gomphognathus 
(Broom 711, pp. 921-922) the pair of alisphenoids are seen to 
form a part of the pterygoquadrate series, in so far as they lie 
between the pterygoids and the quadrates. Likewise in embryo 
mammals the cartilaginous alae temporalis are interpreted by 
Broom (’09) as remnants of the cartilaginous pterygoquadrate 
bar of reptiles. 
Broom’s ‘alisphenoid—epipterygoid’ hypothesis is_ greatly 
strengthened by the evidence offered both in the chondrocranium 
