THE DINOCERATA. 



The Dinocerata form a Sub-order of the Amblypoda, an Order which 

 Cope' has defined as follows: "Mammalia with small cerebral hemispheres 

 which leave the olfactory lobes and cerebellum exposed. The feet short and 

 plantigrade, with numerous (in the known genera, five) digits, terminating in 

 flat, hoof-bearing, ungual phalanges. The seven bones of the carpus distinct, 

 the unciform articulating with both lunar and cuneiform. The astragalus flat, 

 without trochlear surface, and attached to the tibia with very little freedom 

 of movement ; its distal extremity divided into two facets, one for the navicular 

 and the other more or less for the cuboid. Molars inserted with enamel, with 

 wide crowns and transverse crests. A post-glenoid process." 



The Order Amblypoda falls into two Sub-orders : 



I. A third trochanter on the femur, and a fossa for the round ligament ; no 

 alisphenoid canal ; superior incisors present Pantodonta. 



II. No third trochanter, nor fossa for the round ligaments ; an alisphenoid 

 canal ; no superior incisors Dinocerata. 



The sub-order Pantodonta includes the genera Coryphodon and Bathmodon. 

 The former is the most characteristic fossil of the Wahsatch group, in the lower 

 Eocene. It has, as the ordinal name indicates, a complete dentition, and is also 

 marked by a very unmodified type of foot. According to Huxley and others, 

 these unspecialized characters and its geological position combine to place it at 

 the bottom of the Perissodactyle scale. 



The sub-order Dinocerata includes at present several genera which widely 

 vary in size and seem to have been peculiar to different portions of the great 

 Eocene Rocky Mountain basin in which they lived. A distinctive character 

 common to all is the possession of a number of paired protuberances upon the 

 upper surface of the head. Another general feature is found in the downward 

 projections from the rami of the lower jaw which were opposite the huge upper 

 canines. These projections, or flanges, underwent various modifications. The 

 nasal bones also supported a small pair of knobs. It is chiefly upon the position 

 of the cranial protuberances, the conformation of the lower jaw, the develop- 



' Cope. Wheeler's Survey, Vol. IV. pp. 178 et seq. 



