70 The Alligator and Its Allies 
internal carotid (15). Another large foramen in 
the exoccipital bone will be seen and described in 
connection with the posterior view of the skull. 
Dorsal to the quadrate and largely bounded by it 
is the wide external auditory meatus (16), which 
leads into the tympanic cavity. This cavity is 
complicated by a number of canals that lead from 
it in various directions. Overhanging the cavity 
and meatus is the squamosal bone, described in 
connection with the dorsal aspect of the skull. 
The Posterior Aspect (Fig. 22). Most of the 
bones seen in this view have already been described. 
The pterygoids (10) form the two prominent, ventro- 
lateral projections, while dorsal to these is the large 
process formed by the quadrate (8) and quadrato- 
jugal (12). The dorsal margin is formed by the 
edges of the parietal (23) and the squamosals (7). 
Immediately below the parietal is the supra- 
occipital (26); it is a small, triangular bone, articu- 
lating above with the parietal and squamosals, 
below with the exoccipitals, and anteriorly with 
the epiotic. It takes no part in the formation of 
the foramen magnum. 
The exoccipitals (13) form the entire boundary of 
the foramen magnum except the narrow ventral 
portion formed by the basioccipital. Each exoccipi- 
tal is a wing-shaped bone, articulating dorsally with 
the squamosal and supraoccipital, ventrally with 
the quadrate, basioccipital, and basisphenoid, and 
anteriorly with the opisthotic. It is pierced by 
