Professor Marsh's Monograph of the Dinocerata. 189 
“In the lower jaw of all the known Dinocerata, there are 
three well developed incisors on each side. They are inserted, 
each by a single root, and are procumbent, all directed well 
forward. 
“The superior canines of Dinoceras are long, decurved, 
trenchant tusks. The crown is covered with enamel, and the 
root extends upward into the base of the maxillary protuber- 
ance, or horn-core. When the animal is young, these tusks 
grow from a persistent pulp, but, in old age, the cavity becomes 
nearly closed. In the male, these tusks are large and powerful, 
and extend downward nearly or quite to the extremity of the 
pendent process of the lower jaw. 
Figure 20.—Upper molar series of Zinoceras stenops, Marsh; seen from below. 
Figure 21.—Lower molar series of same specimen; seen from above. Both 
figures are three-fourths natural size. m, molar; pm, premolar. 
eras, and, in fact, in all of the known Dinocerata, are remark- 
ably short, with the roots well developed, forming a true 
brachyodont dentition, as in all early Tertiary ungulates. _ 
“In each ramus of the lower jaw of Dznoceras, there is a 
close series of six teeth, three of which are premolars, and 
three true molars, These are all inserted each by two roots 
8 is also true of the genus Tinoceras. : 
Am. Jour. Scr.—Tatrp Series, Vou, XXIX, No. 171, Marca, 1885. 
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