1896.] 167 fFarr. 



form. Coalescing with apex of above is a facet extending up on posterior 

 border of bone, wliicli articulates with cuboid. On the proximal surface 

 there is a small facet on the antero-external corner of bone, which articu- 

 lates with the calcaneum by a small facet just above the inferior astraga- 

 lar facet and which seems to be a part of the latter, but on close exami- 

 nation proves to be a distinct facet. In M. bairdi the navicular just 

 touches the calcaneum, but does not have such distinctly marked facets. 

 This character is seen in some individuals, but in all observed specimens 

 the contact is smaller. 



The ecto-cuneiform is high and massive, the breadth being twice the 

 height. The proximal facet for navicular is concave, both antero-pos- 

 teriorly and transversely. The inferior (or distal) facet is concave in 

 both these directions. On the external side it abuts against the cuboid, 

 and this latter seems to have been just equal in length to the combined 

 length of ecto-cuneiform and navicular. It bears no facet either lateral 

 or proximal for metatarsal iv. 



The coossified ento- and meso-cuneiforms show an emphasized condition 

 of that of M. bairdi, in that the tendency of the distal row of tarsal bones 

 to form a closed circle is more marked here. The portion representing 

 meso-cuneiform bears most all of the proximal end of metatarsal ii. The 

 ento-cuneiform is high and compressed transversely and curves strongly 

 backward and around towards the other side of foot. On its inferior 

 surface it bears a facet at its point of contact with metatarsal ii. 



The metatarsus of J/. 5a«ir(Z4 exhibits the following characters : (1) The 

 cuboid which bears metatarsal iv extends down below the external 

 cuneiform which bears M. iii. (2) The meso-cuneiform does not quite 

 reach to level of the ecto-cuneiform. From this it results that M. iv 

 does not quite reach up to level of M. iii, while M. ii reaches above the 

 latter. In M. copei, M. iv extends quite up to the level of JVI. iii, while 

 the meso-cuneiform is not so deep proportionately as in the smaller 

 species. Metatarsal iv is proximally much less reduced than M. ii, but 

 tapers to about the same size distally. It is borne entirely by cuboid. 

 The disproportion in size of the proximal ends of the two lateral meta- 

 podials can hardly be more than an individual character, as we find all 

 degrees of difference in the relative sizes of the two lateral digits in the 

 smaller species. 



In some specimens the two lateral digits are of the same size, in others 

 subequal with the ivth slightly the larger and in others this digit is 

 very much larger than ii. One individual exhibits the very peculiar 

 character of having the lateral metapodials of the same size on one foot, 

 while in the opposite foot the fourth metatarsal is much larger than the 

 second. 



Metatarsal ii is slightly less reduced than in the average individual of 

 M. bairdi. Proximally it bears a large concave facet for the meso-cunei- 

 form and posteriorly there is a small facet by which it abuts against the 

 inferior retroverted edge of the ento-cuneiform. This latter extends 



