So.] The Proboscidia. 201 
ith that in which the order first appears in Europe. The 
atement of Marsh that the genus has been obtained in the 
wer White River beds is an error. (King, Survey 40th par- 
.llel, I ■ 
the oldest North 
mple type of molar. 
The Tetrabelodon brevidens Cope 
American species, and presents a very 
The last superior has but three cross 
smaller number than exists in any other species of the genus. 
The tooth is wide, and the crests are low. They are well 
divided in the middle by a fissure. Their edges are entire, 
but obtuse, and the first and second internal have a thicken- 
ing at the base 
next the me- 
The 
:refoil. 
thicken- 
ings close the 
valleys at their 
base, but soon 
spread apart. 
They are ab- 
sent from the 
ledge, which is 
represented by 
the 
side. 
thick and smooth. Length of molar, 157 n 
second crest, 98 mm. ; elevation of second 
This tooth resembles that of the Mastodon , 
nearly than that of any other North American species, a 
is still more like that of the M. borsoni o{ Europe. The i 
duced number of its crests indicates it as the most primiti 
