276 



PROF. J. C. BWART OX 



From the naiTOw shield-shaped projection {L.X.) vmder the 

 crest (text-fig. 84), a narrow ridge extending towards the foramen 

 magnum divides the lower part of the occiput into two equal 

 portions x-oughened for the attachment of muscles. Between the 

 crest and the upper border of the foramen magnum the occiput 

 is distinctly concave — near the crest it is excavated to a depth 

 of 12 mm. The part of the occiput external to the condyles {C.) 

 is divided by a ridge continuous with the incurved paroccipital 

 processes {P-P-) into two irregidar, more or less concave, rough 

 surfaces. The greatest width across the occipital condyles {€.), 

 is 99 mm. (only 23 mm. less than the space between the 

 infracornual notches): 99x100-h123 (the width of the occiput 

 under the horn-cores) gives an index of 80. The corresponding 

 index in the Urus skull (text-fig. 83) is only 55. 



. Text-fio-. 88. 



Occiput and liorn -coves of an American Bison. 



The frontals neitliev cover the parietals (text-tig. 80, p. 267) nor project beyond the 

 level of the occipital crest, and the horn-cores arc separated by wide gaps 

 from the supra-occipital. 



The part of the occiput above the occipital crest is divided into 

 three portions, \\z. : — a mesial semicircular deeply excavated 

 portion and two lateral portions continuous with the horn-cores 

 externally and the forehead above. The mesial semicircular 

 concave portion (text-fig. 84), 60 mm. wide and 20 mm. deep, has 

 a rough margin, 3 to 6 mm. in thickness, which forms the nearly 

 horizontal border of the mesial frontal protuberance (text- 

 Hg. 86, A). 



From the measurements given it follows that the occiput of 



