1897.] Geologu and Paleontology. 335 
on the Pacific coast.” (Seventeenth Ann. Rept. U.S. Geol. Surv., 
1895-96, Pt. I, 1896.) 
The Position of the Periptychidz.—This family is one of the 
three which I placed in the Condylarthra on the establishment of that 
order, the two others being the Phenacodontide and the Mensco- 
theriide. With regard to its phylogenetic position, I adopted the view 
that it is probably the type from which were derived the order Ambly- 
poda. In asynopsis of the latter order, published in 1884,’ I remark 
(p. 1129), “It was not until later (1877) that I assumed that the 
Diplarthra are descendants of the Amblypoda, although not of either of 
the known orders, but of a theoretical division with bunodont teeth. 
That such a group has existed is rendered extremely probable, in view 
of the existence of the bunodont Proboscidia and Condylarthra. This 
hypothetical suborder has been called Amblypoda Hyodonta.” * * 
“The existence of Amblypoda Hyodonta is rendered almost certain by 
the discovery that the genus Trigonolestes® of the Wasatch epoch is an 
artiodactyle with tritubercular bunodont superior molars. The ancestral 
type of such a form must have been a tritubercular bunodont amblypod. 
Pantolambda is such a form with the tubercles modified into Vs. 
Moreover, such a type (Amblypoda Hyodonta) would be derived from a 
a Periptychid Taxeopod, with but little modification of the latter. A 
distinct facet of the astragulus for the cuboid bone, and probably a 
change of the carpus by an articulation of the unciform and lunar bones 
would be all that would be necessary. The discovery of Pantolambda 
has increased the probability of such a change having taken place in 
the hind foot, since the astragalus is intermediate in form between those _ 
of Coryphodon and Periptychus.” 
I have never concealed from myself the possibility that the Perip- 
tychide themselves might prove to be the Amblypoda Hyodonta. The 
astragulus has a considerable articulation with the cuboid bone, which 
has an obscure angular distinction from the facet for the navicular. 
So far as this articulation goes the family might be placed in the 
Amblypoda. I have awaited the discovery of the carpus of the Perip- 
tychidæ from that day to this (seventeen years) ; but success has not 
attended the efforts of Osborn and Wortman, who have searched for it. 
It is now, however, time to remark, that as there has been no other type 
discovered which could represent the Amblypoda Hyodonta, the proba- 
bility that the Periptychide are that type, is increased. It is eminently 
_ 7 AMERICAN NATURALIST, 1884, p. 1110. 
*“ Pantolestes” in the original—Trigonolestes brachystomus, which is not a 
aes 
