356 Bulletin American Museum of Natural History. [Vol. XXVII, 



Along with these peculiar specializations some primitive features also 

 survive: The dental formula is xTxl:! ^^^^ nasals spread somewhat 

 posteriorly {fide Cope's figure), there is a long low sagittal crest and the 

 orbit is broadly continuous with the temporal fossa; the tibia also is long 

 and slender, distally acuminate, the head flares widely on the fibular side. 

 The tibia seems to represent an exaggeration of the type seen in the Creodont 

 Sinopa (cf Matthew, 1906, i). 227, fig. 19). Resemblances to the Creo- 

 donta are seen in the large lumbar vertebrfe, the long slender humerus with 

 a very large sub-globular head, a supratrochlear and an entepicondylar 

 foramen, a long deltoid crest and a large great tuberosity. The astragalus 

 approximates the Siuopa type; the carpus retains a free centrale and a 

 lunar-imciform contact (p. 447). 



In short, Meniscotherium appears to be an advanced, early derivative of 

 the Insectivore-Creodont-Condylarth stock, allied remotely to the Phena- 

 codontidte. It resembles the short footed orders Hyracoidea, Proboscidea 

 and others in the length of its humerus and femur, in the small size of the 

 lunar unciform facet and consequent tendency for the carpus to become 

 serial, and in its relatively short metacarpals. Its cheek teeth, however, 

 have too complex a pattern to be prototypal to those of any later order. It 

 parallels Ilyrax in some inconclusive features (p. 362) but it distinctly re- 

 sembles some of the extinct South American ungulates {e. g., TricjonostyJopsi) 

 in the characters of the astragalus and calcaneum {cf. p. 384). 



III. Genetic Relations of the Condylarthra, Taligrada, and 



Amblypoda. 



The Eocene order Amblypoda as defined by Cope (1884, pp. 600-601, 

 514-517) included the suborders Taligrada Cope (Pantolambdida?), Panto- 

 donta Cope (Coryphodontidse) and Dinocerata Marsh (Uintatheriidae). 

 Osborn (1898, pp. 169-218), who elucidated the evolution of the order and 

 gave evidence of its derivation from the Creodont stock, revised the classifi- 

 cation of the Taligrada and Pantodonta and added to the former the family 

 Periptychidpe Cope {cf. Osborn and Earle, 1895, pp. 52-64) Avhich Cope had 

 placed in the Condylarthra. INIatthew (1897, pp. 294-299) revised the 

 Periptychidie but regards them as properly falling under the definition of 

 the order Condylarthra. 



The morphological relations of these two orders may be indicated briefly 

 as follows. (The Mioclaenidie (Osborn and Earle, /. c, pp. 48-52), which 

 are doubtfully referred to this group are not discussed.) 



