762 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



remains to show that they had a very decided backward inclination, as 

 noted by Richardson, who states that the horn cores — 



Are more depressed at the base or llattened on the concave side tlian those relerred 

 above to IHhoii jj/v'scw/s ?,' and they are directed horizontally with a slight basilar incli- 

 nation and more iniad, ranch in the way that the horns of the muslitnsh (IHnon bison) 

 would curve were that animal horned on a much larger scale. Their backward posi- 

 tion is such that a spot on their posterior edge 2 inches from their base is even with 

 the sides of the occipital arch when the ekull is seen in prolile. Though the cores 

 are much wasted by decay, they are still considerably larger than those of an adult 

 mushtush or aurochs bull. 



This backward Hare is very characteristic of crassicorniSj as may be 

 seen by reference to Phites LXXIII, LXXVI and the figures below, 

 where the great differences between the horn cores of B. anUquus, 

 crassirornis, and oceidentalis are well shown. 



Fig. 1.— Bifpekences in corvatukk of horn cores of (1) Bison cuassicornis, (2) B. occidentalis, 



(3) B. ANTIQDUS. 



TSTo. 1 of these figures is from the small, complete specimen shown by 

 Richardson,' No. 2 is Bison oceidentalis in the University of Kansas, 

 and No. 3 is Bison antiquus from the specimen in the Academy of 

 Natural Sciences, Philadelphia, named by Rhoads B. californicus. The 

 identity of this species is discussed under Jiison antiquus. 



The type of Bison antiquus is an imperfect, waterworn, right-horn 

 core, which, however, shows the horn cores to be but moderately long, 

 with the transverse diameter but little greater than the vertical, 

 although this character is much exaggerated owing to the wearing 

 away of the upper surface as shown in the plate. The horn cores of B. 

 antiquus, as noted in the diagnosis of that species, stand out almost at 



' This is the "spikehorn" figured on Plate LXXVI of this paper. 

 2 Zoology of the Voyage of the Herald, pi. vii, fig. 1. 



