scott: toxodonta OF THE SANTA CRUZ beds. 143 
The tubular auditory meatus, the aperture of which has the same elevated 
position as in Nesodon , is much more extensively exposed between the 
postglenoid and post-tympanic processes than in the latter. No part of 
the mastoid portion of the periotic would appear to be visible and, of 
Fig. 20. 
course, there is no mastoid process, the paroccipital processes forming the 
infero-external angles of the occipital surface, as in Protypotherium and 
the immature Nesodon. 
The sagittal crest is much shorter and widens very gradually into the 
broad forehead, which has a sudden, though short, descent to the nasals; 
The orbits have a more elevated position, their roof rising a little above 
the level of the forehead. The postorbital processes of the frontals are 
