170 BULLETIN OF THE 



and it is therefore unnecessary to dwell npon it here further than to remark 

 its very close resemblance in many important respects to the the eocene genus 

 Hyrachyus. In general there are also certain analogies with the horse, in the 

 delicate head, long neck, and elongated and narrow I'eet. 



Hyracodon major, sp. nov. The type of this species is a fairly complete 

 skeleton in the Princeton Museum, and in the Camljridge collection it is rep- 

 resented by a beautifully preserved fore-foot. Of this the carpus is high and 

 narrow ; the scaphoid is less produced laterally than in Aceratherium, the facet 

 for the trapezium is very small and infero-lateral in position, those for the 

 trapezoid and magnum much larger, and nearly equal in size. The lunar is 

 contracted and anteriorly rests only upon the unciform, touching the magnum 

 laterally, while in H. nebrascense there is apparently no anterior contact be- 

 tween the lunar and magnum. The cuneiform is high and much compressed, 

 and the pisiform is short, compressed, and much expanded at the free end. 

 The trapezium is a very small bone ; it is pushed to the posterior side of the 

 trapezoid so as not to be visible from the front, and has no contact with meta- 

 carpal II. The trapezoid is well developed, though relatively smaller than in 

 the rhinoceros. The magnum is very large, in accordance with the develop- 

 ment of the third digit, and is especially elongated in the vertical direction. 

 The unciform is very high and narrow, and descends much below the level of 

 the other carpals ; owing to this compression the facet for metacarpal III. is 

 entirely lateral instead of distal ; there is an unusually extensive contact be- 

 tween the unciform and the magnum. 



The lateral metacarpals are slender, narrow, and curved, the median one 

 considerably longer and much heavier. Metacarpal 11. abuts against the mag- 

 num by a considerable facet, while in H. nebrascense the facet is very small. 

 Metacarpal V. is represented by a minute nodular bone, which is attached to 

 the unciform and to the ulnar side of metacarpal IV. 



Measurements. H. nebrascense. H. major. 



M. M. 



Carpus, breadth 040 .060 



" height (median line) 033 .050 



Unciform; width 020 .023 



" height 021 .033 



Metacarpal II., length — .115 



" III., " — .128 



« IV., " — .105 



« v., " 010 — 



Hyracodon (?) planiceps, sp. nov. This large species is distinguished 

 from H. nebrascense by its extremely low and broad cranium, which is flattened 

 upon the upper surface and entirely lacks the sagittal crest, which is repre- 

 sented by two ridges diverging from the supra-occipital border. This flat- 

 tening alters the proportions of the occiput and temporal fossa. Comparing 



