126 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DcC. 19, 



three fossils closely agree with each other, as they do likewise with 

 the figure of the Siberian fossil cranium given by Pallas, and repro- 

 duced by Cuvier in pi. xii. figs. 10 & 1 1 of the ' Ossemens Fossiles*.' 



The first difference between the fossils and the recent skull is the 

 somewhat greater extent, in the latter, of the vertical plate of bone 

 between the superoccipital ridge and the back part of the bases of 

 the horn-cores. In the English fossil the still persistent lambdoidal 

 or superoccipital suture crosses transversely the corresponding tract. 

 In the Siberian fossil and the recent cranium that suture is oblite- 

 rated ; they are. both from older individuals ; but the tract in the 

 recent skull is smoother and more convex, as well as more extensive. 

 The value, however, of this character is diminished by the fact that, 

 in the cranium of the recent Musk-buffalo, a bull of between four 

 and five years old, figured from behind, of the natural size, in the 

 " Fossil Mammals of the Herald," pi. iii., the tract between the super- 

 occipital ridge and the horn-cores is not greater than in the English 

 fossil, and it is equally traversed by the lambdoidal suture, showing 

 that that suture is retained until the animal has acquired its full 

 size, and up to the fifth year. Sir John Richardson gives no other 

 view of that recent skull, of the natural size, with the horn-cores ex- 

 posed. Comparing, therefore, the fossil crania with the cranium of 

 the old Musk-bull from Melville Island, the bases of the horn-cores, 

 though similar in size and rugosity, slope down at their upper sur- 

 face, as they extend from the median fossa outwards, more directly 

 and gradually, and the interval between their inferior surface and the 

 side of the cranium is narrower and more angular in the recent skull, 

 but is wider and more arched in the fossil : in this respect, however, 

 there appears to be a difference between the skull of the old Musk- 

 bull and that of the younger Musk-bull figured by Sir J. Richardson, 

 in which the curve of the basal part of the horn-cores rather more 

 resembles that in the fossil skulls. 



The cranium from Maidenhead is the only one of these that has 

 an entire horn-core ; the right one, at least, wants only a small part 

 of the tip. 



Comparing the recent (fig. 6) and fossil (fig. 3) crania in a side 

 view, the horn-core in the recent is less vertically deflected, and is 

 bent in a slight degree more outwards and forwards at the tip. This 

 character, however, is not so strongly marked in the figure of the 

 young Musk-bull above cited, as in the old Musk-bull before me. 



The deep and narrow longitudinal groove, extending along the 

 middle of tbe upper surface of the cranium, and dividing the broad 

 bases of the horn-cores, is similar in, and equally characteristic of, 

 the fossil (fig. 2) and recent (fig. 5) crania compared. The lower 

 surface of the base of the horn-core is continued more directly from 

 the side-wall of the cranium, outwards and downwards, in the recent 

 cranium : in the fossil crania that part of the base of the horn-core 

 rises before it curves outwards, and thus the space between the zygo- 

 matic arch and the horn-core is greater in the fossil (fig. 1) than in the 

 recent (fig. 4) skull. The outer surface of the horn-core is divided from 



* Tom. iv. 4to. 1823. 



