1910.] The Amhlyvoda. 359 



Feet more slender, tridactyly progressive. Astragalus with slender 

 neck; trochlea keeled. Lunar-unciform facet becoming reduced, carpals 

 becoming serial. M\ m^ early becoming quadrate, with large hypocone. 

 Premolars triangular, with tritocone. 



Amblypoda (Cope) Osborn. (Including the Periptychidae, Pantolamb- 

 didse, Coryphodontidae, Uintatheriidse) . 



Digits becoming stout and short, pentadactyly unreduced. Astragalus 

 with neck progressively broadening and trochlea flattening; with cuboid 

 contact. 



Lunar-unciform facet broad, carpals becoming displaced toward the 

 ulnar side [Pantolambda). M', m- persistently trigonal, protocone remain- 

 ing central, hypocone small. Premolars bicuspid, without tritocone. 



Matthew (/. c, p. 29.5) having in mind on the one hand the great struc- 

 tural interval between Periptychus and the highly specialized Amblypods 

 and on the other the resemblance of the smaller Periptychidae (Anisonchinse) 

 to the Condylarthra, placed the family in the latter order and showed that 

 the two orders were so closely connected in the Basal Eocene that the syste- 

 matic position of the Periptychidae is largely a question of definitions. 



The Basal Eocene families of the Condylarthra and "Taligrada" seem 

 in fact to be not widely removed from each other, and there is evidence that 

 the broad "horizontal" group of which they were doubtless a small part 

 had about the same relation to certain of the more highly specialized ungulate 

 orders that the most primitive Creodonta (including the Miacidae) had to 

 the later Creodonta, Fissipedia and Pinnipedia. These "protungulates" 

 retained very many Creodont characters in the skull and skeleton and were 

 separated from that group chiefly by the greater elaboration of the molar 

 teeth. 



Probably the most primitive members of the series are the smaller Peri- 

 ptychidae, especially Haploconus lineatus Cope (1884, pi. xxve, figs. 1-4) the 

 dentition of which exhibits the following interesting features: 



The premaxillaries may have been prolonged as in Insectivores, the 

 canines are not large. The bicuspid p* is larger than the small narrow 

 tritubercular molars. The internal basal apex of the molars is a prominent 

 hypocone spur (c/. certain Zalambdodont Insectivores). The chin is 

 shallow, the lower premolars are narrow, the lower molars lack the paraconid. 

 The ])alate is broad and well ossified. 



This small species, the teeth of which were no larger than those in Dasy- 

 urus viverrinus, may have been omnivorous to insectivorous-carnivorous in 

 diet. It is allied with the much larger Periptychus by way of Conacodon 

 (cf. Osborn, 1907, p. 165). Osborn and Earle (1895, p. 63) suggested that the 



