72 



THE CERATOPSIA 



both fully ossified specimens, while that of flabellatus is very young, so that the partition may still 

 have been cartilaginous. One assumes that the olfactory nerves themselves were always paired and 

 that the sense of smell was amply developed. The cerebrum, on the other hand, was small in pro- 

 portion to the bulk of the brain as a whole, which gives evidence of an extremely low grade of intelli- 

 gence, compared with mammalian standards. The cerebellum is relatively large and is followed by 

 a distinct constriction of the mass, as viewed from above, the cranial cavity expanding again for 

 the reception of the enlarged medulla oblongata. In the region of the constriction lay the otic mass, 

 including the semicircular canals, which are beautifully preserved in the Anchiceratops specimen 



O.so 



Fig. 31. — Left side of longitudinal section of skull, showing brain cavity of Triceratofs, from No. 5740 U.S.N.M., about 

 Y% natural size. B. oc.fr., basioccipital process; car, foramen for left carotid artery; D.so., anterior end of dermo-supra- 

 occipital [parietal] ; F., posterior portion of frontal; Mx., maxillary; Oc, occipital condyle; P., parietal [supraoccipital] ; 

 ■pin., pineal foramen[?]i fi'-f-y pituitary fossa; P/.f., postfrontal; pf.f.f., postfrontal fontanelle; S.oc, supraoccipital 

 [exoccipital] ; v, foramina for exit of supposed veins; /, //, ///, IV, V, VI, VII, VIII, IX, X, XII, foramina for exit of 

 cephalic nerves of corresponding numbers. (Figure and legend after Gilmore.) 



(PI. XI). The foramina for the emission of the cerebral nerves are large and clearly defined, but 

 in the interpretation of some of them Brown, Hatcher, and Gilmore differed, nor am I able to come 

 to any more definite conclusions. Brown's interpretations for Anchiceratops, as indicated in the 

 legend of PL XI, are the latest and most acceptable. 



One innovation in the brain cast of a Trachodon, as well as in that of the Anchiceratops described 

 by Brown, is the demonstration of the semi-circular canals, the seat of the organ of equilibration. 

 "These canals," according to Brown, 3 "have the normal reptilian position and open freely from one 

 to the other with distinct ampullae at the origin, but the horizontal is much shorter and smaller than 

 either the anterior or posterior divisions." The cochlea if present was not preserved. Something 



3 Brown, B., 1914, A, pp. 546-547. 



