MORPHOLOGICAL REVISION 



131 



bility of its union, either by suture or fracture, with the lateral walls of the 

 skull. In front the vacuity continues in a shallow, lateral groove, nearly 

 as far forward as the orbital margin. On the right side, the upper margin 

 of the vacuity, as stated, is not preserved, but the natural, rounded border 

 of the opening is found on the lower and partly on the front side, giving, 

 with the left side, practically the outline of the vacuity throughout, save 

 at the narrowed posterior end. The cavity was oval in shape, about twenty 

 millimeters in length, looking outward, and a little upward and forward. 



Fig. 46. — Trematops milleri. No. 640 Univ. of Chicago. X \ < 

 Restoration of skeleton. According to Williston. 



There remains the bare possibility that the enlarged vacuity was connected 

 by a slender and sinuous isthmus with the outer posterior margin of the 

 skull, but I do not think so. In position, it is seen that the fenestra is nothing 

 more or less than a greatly elongated and closed epiotic notch, and this 

 interpretation is confirmed by the disposition of the bones on the under, 

 palatal side of the skull. Other genera of stegocephs have the epiotic notch 

 closed posteriorly, but I know of none in which it extends nearly so far for- 

 ward as it does in this genus. As an epiotic vacuity it conveys the sugges- 

 tion that the origin of the lateral temporal vacuity in the double-arched or 



