On a fossil Ox from the Mississippi. 283 



with a reddish-brown substance, possibly the vestige of a pe- 

 riosteum. And the whole surface is marked by numerous 

 protuberances and rugosities, which had doubtless been cover- 

 ed by the bases of the horns. Four cells of different sizes 

 and irregular shape, and three small and regular foramina, 

 are observed in the frontal depression. They communicate 

 with similar cells in the horn processes, and the regularity 

 of the smaller foramina, would lead to a belief that they 

 served for the passage of nutritive vessels to these cells. One 

 of them (the lowest on the right side) when freed from the 

 sand and charcoal which obstructed it, was traced to one of 

 the frontal sinuses. The length of this depression, from its 

 most elevated part to the place where the bones of the face 

 are broken off, is seven inches. Its depth was measured by 

 drawing a line across the flat anterior surface of the horn 

 processes. The distance from this line to the centre of the 

 depression was 1-5. From the centre of this depressed por- 

 tion, where a slight and nearly obliterated fissure seems to 

 mark the place of a former suture, a line drawn over the an- 

 terior surface of the most entire horn process to its extremity, 

 was nine inches. 



The posterior part of the cranium is composed of the parie- 

 tal and occipital, but there is nothing visible in this specimen 

 to define their boundaries. It is only by the rugosities for 

 the insertion of the requisite cervical muscles, that we are en- 

 abled to conjecture the original place of the sutures; and the 

 crest of the parietal is so far obliterated, that this latter makes 

 with the posterior part of the frontal, and with the occipital 

 bone, almost a continuous plane. 



The width of the skull across the narrowest part is 4*7 ; 

 but as this is wider than the actual transverse diameter of the 

 cranium through its centre, which it will be recollected was 

 only 4-5. Hence it may be stated, that the sides of the 

 cranium approach each other as they descend. The sides of 

 the head are much compressed, and three distinct parallel 



