Measurements of Tarsus. M. 



Greatest diameters of astragalus 



anteroposterior 038 



transverse 035 



Width between centres of trochlear crests 015 



Transverse extent of navicular facet 021 



" " cuboid OOG 



! longitudinal 008 

 anteroposterior 024 

 transverse 027 



C longitudinal 007 



Diameters of ectocunciTorm -| anteroposterior 019 



(^ transverse . . . 025 



The metatarsals are smaller than those of the undetermined Protohippus 

 and still smaller than those o( Ancliitherium prcestans. The third is of gen- 

 erally similar form in all three of the species, though the proximal extrem- 

 ity has not quite so much anteroposterior width in H. isonesum as in the 

 other species. In all of them it is more convex than in the horse. It also 

 differs from that of the horse in not having the posterior facet cut off from 

 the anterior. It is partially cut off by a deep sinus in this species and the 

 undetermined Protohippus, which sinus is only represented by a notch in 

 A. prmstans. The lateral metatarsals are slender medially as in the unde- 

 termined Protohippus, and not so stout nor so much compressed in Anchi- 

 therium prastans. They do not quite reach to the articular surface of the 

 median metatarsal, being a very little shorter than in the Protohippus and 

 Anchitherium mentioned. The phalanges of the H. isonesum have about 

 the same diameter as those of the undetermined Protohippus, but they 

 are distinctly shorter, especially the pastern. The coffin bone differs from 

 that of the same species in the smaller size of the proximal lateral fossae. 



Measurements of Foot. M. 



Length of m.t. iii 175 



Proximal diameters m.t. iii \ anteroposterior 019 



c transverse 025 



Diameters shaft m.t. iii \ anteroposterior 015 



c transverse 018 



Distal diameter m. t. iii \ anteroposterior 019 



' transverse 021 



Length m. t. iv 159 



Anteroposterior diameter m. t. iv, proximally 020 



" ii, " 014 



" " " ii, medially 006 



Length of pastern laterally 033 



Width of do. distally 019 



Length of coronary on side 025 



Width of do. distally 019 



Length of coffin bone in front 031 



Expanse of do. posteriorly 030 



