622 The Phylogeny of the Camelide. [July, 
The most specialized of all the genera of Camelidæ, Eschatius 
Cope, extended its range from Oregon to the valley of Mexico- 
I owe to the courtesy of my friend Dr. Mariano Barcena, formerly 
director of that department of the Museo National of the City of 
Mexico, the opportunity of inspecting specimens of the jaws and 
teeth of this genus. It is represented by two species. The larger, 
E. conidens Cope, was about as large as a camel or dromedary. It 
ranged from the valley of Mexico to Oregon; specimens found 
by Mr. Sternberg in the latter region not being distinguishable 
from those of the Mexican origin. The second species, Æ. /ongt- 
rostris, is a good deal smaller, and is only known from the same 
Equus beds of Oregon which have yielded the larger one. 
The succession of structure in the leading genera of the selen- 
odont or tylopod part of this phylogeny may be represented as 
follows : No cannon bone. Cannon bone present. 
Incisor teeth present. Incisors one and two wanting. 
A ee i 
r $, 4 
4 premolars. 3 prem’s.! 2 prem’s, 1 premt. : 
Lower Miocene { Potbrotherium. : 
Protolabis. 
Upper Miocene Procamelus. : 
Pliauchentia. 
i Camelus. 
_ Pliocene and recent - Auchenia. 
This table shows that geological time has witnessed, in the his- 
PAN tory of the Camelidæ, the consolidation of the 
bak bones of the feet and a great reduction in the 
numbers of the incisor and premolar teeth. ihe 
embryonic history of these parts is as foliows : 
In the feetal state all the Ruminantia (to which 
the camels belong) have the cannon bones divided 
as in Poébrotherium ; they exhibit also ince 
teeth, as in that genus and Protolabis. Very 
Fic. 13 —Castof young recent camels have the additional premolar 
ain of Poébro- of Pliauchenia. They shed this tooth at an ped 
nat. size. From period, but very rarely a camel is found in y = 
i seum, the tooth persists. The anterior premolar A = 
Princeton, N.J. normal Camelus is in like manner found ag : 
young llama (Auchenia), but is shed long before the animal at 
_ tains maturity. I may add that in some species of P rocamelus 
-caducous scales of enamel and dentine in shallow cavities er 
_ Sent the incisive dentition of Protolabis, 
“Mn lower jaw, 
