no. 2086. SOME MAMMALS OF THE PLEISTOCENE— HAY. 525 



48 mm., the vertical 41 mm. The horn-cores descend less as they pass 

 outward than they do in either B. homhifrons or B. sargenti. When a 

 cord is stretched from the tip of one horn-core to that of the other it 

 passes but little in front of the rear of the orbit and above what would 

 evidently have been the lower border of this. The cord is on a level 

 with the roof of the brain cavity. 



The horn-cores may be said to stand on short pedicels and to have 

 a burr, as in the bisons. On the upper surface, however, the exostosis 

 has just begun to spread on the forehead and has hidden the pedicel. 

 The condition is intermediate between that seen in B. homhifrons, 

 with an evident pedicel, and that of B. sargenti, in which the exostosis 

 has advanced well on the forehead. 



The parietal bone is a mass which contains numerous small cavities, 

 like those of a fine sponge. The frontals, 60 mm. thick at the mid- 

 line, are occupied by large air cells, some of which open into the bases 

 of the horn-cores. The plane of that part of the upper surface of 

 the skull which is behind the horn-cores makes an angle of about 

 47° with the plane of the anterior part. The angle in B. sargenti 

 appears to be about the same as in B. nivicolens. Considering all the 

 facts, the writer is compelled to place both these species just men- 

 tioned in the genus Bootherium. 



Because of the direction taken by the horns, more outward and less 

 downward, B. nivicolens is evidently distinct from both the other 

 species. By its long slender horn-cores, carried far in advance of 

 the orbits, B. sargenti is distinguished from B. homhifrons. 



BOOTHERIUM SARGENTI Gidley. 



This species was described by J. W. Gidley in 1908. 1 The de- 

 scriber's figures present views of the partial skull as seen from in 

 front, from the left side, and from above. His description is brief, 

 and no measurements were presented. Neither are the relative sizes 

 of the figures given; but the statement was made that the size was 

 about two-thirds that of Ovihus moschatus and somewhat greater than 

 that of Bootherium homhifrons. Wishing to study the specimen at 

 first hand the present writer, in January of the year 1914, visited 

 the Kent Scientific Museum at Grand Rapids, Michigan, where the 

 specimen is deposited. Opportunity to examine this and other 

 Pleistocene materials was freely given by the director of the mu- 

 seum, Mr. H. E. Sargent. 



The specimen was found, as stated in the original description, in 

 the Moorland swamp, on the farm of Mr. Charles McKay, near 

 Grand Rapids, Michigan. Mr. McKay has kindly informed the 

 writer that the exact locality is in the northwest quarter of the 

 northeast quarter of section 16, in township 10 north, range 14 west. 



i Proc. U. S. Nat. Mus., vol. 34, p. 683, pi. 79. 



