378 



THE EOCENE PERIOD. 



zoides and magnum are more variable in their proportions than is tlie cunei- 

 form. This is directly due to the fact that the reduction of tlie inner two 

 digits is more usual than the reduction of 

 the external two. I therefore view the rela- 

 tions of these bones as more characteristic. 

 In the tarsus the really variable bone is the 

 cuboid. It is by its extension inwards that 

 the additional facet of the astragalus is pro- 

 duced. Its relations will therefore be con- 

 sidered rather than that of the astragalus in 

 framing the following definitions : 

 Order I. Staphoides supported b.v trapezoides and 

 A not by magnum, which supports lunar. Cuboid 



nrO 



Fig. 10.— Left pos- Order III 



articulating i)roximally with calcaneuni only. 



Taxeopoda. 

 Order II. Scaphoides supported by trapezoides, 



terior Toot of Phena- and not by magnum, which with iincilbrin sup- 



Fig. 17.— KigUt po8- 

 and not by magnum, winch .supports lunar. ,^.^j^^ ^^.^.^ ^^ ^^^^^ 



Cuboid extciulcd inwards and articulating with odpensis (from c a vier). 



the distal t;u;e of the navicular.. . .Proboscidea. Ca. cilcaiK-nm : a. as- 



Scaphoides supported by trapezoides trngaUis;M. navicular; 



CM. cuboid ; ecc. ecto- 



codus primcnus. one- ^j.^^ ^]^^ i^^ar. Cuboid extended inwards and cuneiform ; "enc. enti 



iir( Dft ura size articulating with astragalus Amblypoda. QuneHoim. Nat. size. 



(origuial). o o 



Order IV. Scaphoides supported by magnum, which with the unciform also supports 



the liuiar. Cuboid extended inwards so as to articulate with the astragalus. 



Diplarthra. 



The sub-orders are defined as follows: 



I. TaXE0P0D4. 



There are two, perhaps three sub-orders of the Taxeopoda, the Hyra- 

 coidea, the Condyhrthra, and perhaps the Toxodontia? The Toxodontia are 

 however not sufficiently known for final reference.* The sub-orders are 

 defined as follows: 

 A jioHt glenoid process; no fibular fiUM't of calcaneum, but an interlocking articulation 



between fibida and astragalus; ungual i)lialanges truncjit* Hyracoidea. 



A post-glenoid i)r(K;ess; no tibular facets on either wilcaneum or astragalus; a third 



trochanter of the fennir; ungual phalanges acuminate Condylarthra. 



' See my remarks on Toxo<lon, Prncep<liiif;H Amer. Pbilosoph. Society, 1881, p. 402. 

 'The cousidenible reneniblancc lii'twecii the drntition of Tozodon and ffj/rax mnit not be over- 

 looked. 



