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1884.] The Amblypoda, IIHI 
ence of a postglenoid process; the presence of enamel on the 
teeth, and the absence of any teeth growing from persistent pulps. 
The superior molar teeth are constructed on the tritubercular 
Mammalia presenting the above combination of characters first 
appear in the Puerco Eocene epoch, and continue through the 
Wasatch and Bridger epochs, and then disappear. They have 
not been found in later deposits. The Puerco species are small- 
est in dimensions, while those of the Bridger epoch are the 
largest of Eocene Mammalia, equaling in the size of some of 
their bones the largest of living terrestrial Mammalia. Besides 
their great size the species of the Bridger epoch prove the ancient 
exuberance of their growth-energy in the development of extra- 
ordinary processes and horns on the head and large and formida- 
ble canine teeth. 
Three suborders represent this order. Each one is confined to 
a distinct horizon of the Eocene period, with one doubtful excep- 
tion. The characters are as follows: 
Astragalus with a head; a third trochanter of femur; superior incisors. . Tadigrada. 
No head of astragalus; a third trochanter; superior incisors......-++.- P. 
No head of astragalus, nor third trochanter, nor superior incisors.....- 
The Taligrada only occur in the Puerco epoch, the Pantodonta 
are confined to the Wasatch, and the Dinocerata belong to the ~ 
dger epoch, one species having been found extending down- 
wards into the Wasatch, unless there be some error.’ 
Tue TALIGRADA. 
The Taligrada are represented by one family, and one genus, 
Pantolambda Cope.? This form is interesting on various accounts. 
It furnishes the only known example of a tritubercular seleno- 
nt superior molar dentition. That is, each of the three cusps 
of which the crown of the superior molar is composed, is a well- 
formed V (Fig. 34). We shall see later on, that this form ex- 
Plains the origin of the peculiar molars of some of the Panto- 
donta, Its astragalus is of remarkable form, which is interme- 
diate between that presented by the other members of the order, 
and the diplarthrous ungulates, as for instance, the rhinoceroses 
(Fig. 3, fig. d a” a"). It has the flat tibial face characteristic of 
all the Puerco mammals, and of many of those of the Wasatch 
«This is the Bathyopsis fissidens Cope. 
See NATURALIST, 1883, p. 406. 
