282 On a fossil Ox from the Mississippi. 



This organic relic may be described as quadrangular in its 

 form, truncated obliquely at the base, where the sphenoid goes 

 off posteriorly, to meet the occipital process of the temporal 

 bone. The following are its dimensions in English inches 

 and tenths. 



From the summit of the condyloid processes of the oc- 

 cipital foramen, to a line drawn across the anterior surfaces 

 of the horns 8*1. The distance in a straight line between 

 the mastoid processes of the temporal bones 7*3 ; but it 

 should be remarked that this last measurement is merely 

 an approximation, as the mastoid processes are much worn 

 down and rounded. Diameter of the skull over the foramen 

 ovale 4*5. 



The horn processes are of a flattened shape, and make a 

 sudden turn downwards, almost immediately after originating 

 the cranium. It is impossible from the fragments that remain, 

 to judge whether they subsequently turn outwards or forwards. 

 The more entire of the two, is on the left side. It is nearly 

 complete for the distance of three inches. On the opposite 

 side it is broken off short, at a distance of 2*5 from its base. 

 The longest portion is 6*5 in length, measured along the 

 anterior convexity of the bone. The circumference at the base 

 is eleven inches, the longest diameter 4, and the shortest 2*5. 

 The circumference at the base, and distance in a strait line 

 between the fractured ends of the horn processes 13*3. 



These processes arise entirely from the anterior part of the 

 frontal bone, and their longest diameter is in the same plane 

 with the bones of the face. They are separated from each 

 other bj'a large hollow or depression, which was so dissimilar 

 to any thing observed among the animals whose structure we 

 had observed, that it was at first supposed there must have been 

 an entire destruction of the greater portion of the frontal bone. 

 We shall, however, have occasion to show that this is a natu- 

 ral appearance, analogous to what has been observed among 

 a few living animals. This depression is apparently covered 



