No. 3.] OSTEOLOGY OF MESOHIPPUS AND LEPTOMERYX. 355 



Fig. G. — Right can- 

 non-bone of Leptomeryx 

 Evansi ; showing the ru- 

 dimentary mt. II : natu- 

 ral size. Cope collection. 



reduced ; its proximal end forms a short, sharp spine, co-ossified 

 with the tibia ; the distal end is generally free, and in this case 

 forms a nodule wedged in between the distal end of the tibia 

 and the calcaneum. In one specimen, however, which may 

 possibly belong to a different but closely allied form, the distal 

 end of the fibula is co-ossified with the 

 tibia, forming an external malleolus, just 

 as in the chevrotains. A similar variabil- 

 ity in the fibula is to be found in Dorcathe- 

 rinm (Flower, No. 17, p. 180). 



The pes, as Cope has shown, is more 

 like that of the Pecora than of the Tragu- 

 lina. The astragalus is higher and nar- 

 rower than in Tragidus ; the calcaneum 

 is rather shorter. The cuboid and navicu- 

 lar have coalesced, as have also the meso- 

 and ecto-cuneiforms. Cope states that 

 "the ecto- and meso-cuneiforms are dis- 

 tinct, and there is no ento-cuneiform " (No. 10, p. 405), but this 

 is a mistake. The ento-cuneiform is present, and the other two 

 are co-ossified, just as in the ordinary ruminants. 



The third and fourth metatarsals have coalesced into a 

 cannon-bone, which is extremely like that of Tragidus in 

 appearance and relative length, but is decid- 

 edly more slender, and as in that genus the 

 carinae appear only on the plantar side. The 

 lateral digits, however, are very different, as 

 only the proximal ends are preserved, and 

 these have coalesced with the cannon-bone, 

 just as in the true ruminants. The limits of 

 metatarsals II. and V. are still plainly visible 

 in the compound bone. Except for the posi- 

 tion of the distal carinae of the cannon- 

 bone, therefore, the tarsus and metatarsus 

 of Leptomeryx show all the characteristics 

 of the Pecora. The contrast between the 

 condition of the manus and that of the pes 

 in this genus is, as Cope has remarked, quite unparalleled. 



The phalanges resemble those of the fore foot, but, as in 

 Tragidus, they are considerably larger than the latter. 



Fig. H. — Proximal 

 and ungual phalanges 

 of the pes of Lepto- 

 meryx Evansi; nat- 

 ural size. Cope col- 

 lection. 



