26 



Width of proximal surfaces (antero-posterior) -oig 



Transverse diameter of shaft -022 



Antero-posterior diameter of distal articulation -018 



Transverse diameter of distal articulation -018 



The tarsus. — The astragalus (Plate IX., Fig. 5) has the 

 condyles asymmetrical and divided by a deep groove ; the 

 head is narrow, with the neck elongate. The face for the 

 cuboid is small, and confined to the external border. 



The calcaneiun (Plate IX., Fig. 4) is long and compressed, 

 with its upper and lower margins straight and nearly parallel ; 

 its tuberosity is large. The face for the cuboid is small. 



The navicular (Plate IX., Fig. 6) is proportionately longer 

 and narrower than it is in the modern horse. The internal 

 and middle cuneiforms were probably separate. 



Metatarsals (Plate IX., Fig. 7).— Three in number. Are 

 very much shorter proportionately than in the modern 

 horse. In shape they are compressed and arched forward. 

 The distal ends are flattened vertically, arched forward, and 

 deeply grooved in the middle. 



The phalanges (Plate IX., Fig. 7) are very short, rather 

 stout, and very smooth and convex above. 



The ungual phalanges are very thin and crescent shaped. 



Measurements. 



ASTRAGALUS. 



M. 



Greatest width -029 



Greatest length 022 



Length of navicular facet 'O^? 



Width of navicular facet -012 



Length of tibial trochlex externally 016 



CALCANEUM. 



M. 



Total length "OSS 



Total width 019 



Depth in front •°22 



Length of heel -035 



Depth of heel -o^^ 



Length of cuboid facet '^'^^ 



NAVICULAR. 



M. 



Width "••• •°^9 



T ^u "OIO 



Length 



