464 H. F. shorn — Mammalia in North A 



merica. 



The oldest American Artiodactyl certainly known is the 

 tritubercular Pantolestes of the Wahsatch. Cope believes the 

 line of American Llamas may have sprung from this, and have 

 been continued through Homacodon of the Bridger. The 

 first undoubted cameloid is Leptotragulus of the Uinta, a com- 

 paratively recent discovery. It has strikingly reduced feet for 

 such an early form. Pcebrotherium of the White River and 

 John Day has quite the proportions of the living llama ; 

 thence the line passes into Protolabis of the Beep River and 

 John Day. Scott believes that these forms are undoubtedly 

 related to both the camels and llamas, and that in the Loup 

 Fork, perhaps in the two species of Procamelus, the division 

 occurs, P. angustidens passing into the camels, and P. occi- 

 dentalis into the llamas. The Pliocene Homocamelus, Holo- 

 meniscus and Eschatins, Scott believes may represent a highly 

 specialized side line of camels ; while Pliauchenia, still imper- 

 fectly known, may belong on the llama side. 



The deer represented by Cosoryx and Blastomeryx are, so 

 far as we know, not of American origin, for they first appear 

 in the Upper Miocene at Loup Fork. 



The Ancylopoda. 



The order Ancylopoda Cope presents the most signal excep- 

 tion to the law of correlation. It is only quite recently that 

 Filhol, Forsyth Major and Deperet have brought together the 

 sloth like phalanges with the ungulate type of teeth of the 

 Chalicotheriidse. Since 1825, when Cuvier described the 

 phalanges from Eppelsheim as those of a " pangolin gigan- 

 tesqae" referring to their deep clefts, and 1833, when Kaup 

 named the teeth, these structures were always considered dis- 

 tinct. It is probable that Moropus and other supposed Sloths 

 described by Marsh from our Miocene also belong in this 

 exceptional order. As now restored by Filhol and myself, 

 this remarkable Chalicotherium had a gait less clumsy than 

 the Sloth, and something between a huge cat and a hoofed 

 animal ; it combined the skull of a primitive ungulate with 

 the molars of an eocene titanothere, for the premolars are 

 simple. The limbs, wrist and ankle bones are chiefly ungulate 

 and perissodactyl. In viewing this combination of characters, 

 the first question to settle is which set of characters is second- 

 ary and adaptive. I agree with Deperet, as against Filhol 

 who regards this as an aberrant edentate, that the unguiculate 

 characters are secondary ; but I do not believe it is very near 

 the Perissodactyla. It seems to have sprung rather from the 

 primitive ungulate stem before it had parted with its ungui- 

 culate characters. Perhaps it came off from the Wahsatch 



