204 The American Naturalist, [April, 
with entire palate with both last molar teeth and tusks. The 
superior tusks are compressed distally, and the inferior tusks 
are large and have an enamel band ; they are cylindric. The 
jaws indicate a smaller species, but the molar teeth are as 
large as those of the larger American form of M. angustidens, 
and as long as that of M. americanus, but narrower. Its 
symphysis is not prolonged, and the ramus is low and not com- 
pressed. Length of ramus posterior to symphysis, M. .500; 
of last lower molar, .182 ; width of do., 75. The mental tusk 
is much larger than that of M. productus or M. angustidens. 
Diameter of its alveolus, .068. There are several marked 
peculiarities in this species. The symphysis is remarkably 
short, when we consider the large size of the inferior tusks. 
The superior tusks are remarkably compressed for a consider- 
able part of their length distally, having a vertically oval 
section. From the Loup Fork bed of Kansas. 
Tetrabelodon productus Cope is abundant in the Loup Fork 
beds of New Mexico. It is a species of about the dimensions 
of the T. angustidens Cuv., but the symphysis is not so pro- 
duced, and the ramus of the lower jaw is not compressed and 
elevated. It is the only species in which three superior pre- 
molars have been demonstrated; other species having gener- 
ally two. The second and third true molars are in use at one 
Tetrabelodon campester Cope is a rather large species, with a 
very long symphysis of the lower jaw, and a low ramus. The 
teeth are tetralophodont, and the sixth molar has six cross 
rows of tubercles and a heel. It is in some measure allied to 
the T. longirostris of Europe, but the symphysis is longer, 
and the teeth are more complex. The tusks are cylindric 
and nearly straight, and have a wide band of enamel. The 
known specimens are from the Loup Fork beds of Kansas 
and Nebraska. (Plates IX, X.) 
The Dibelodon shepardi Leidy was founded on an inferior 
sixth molar tooth from California. I subsequently' described 
specimens of the same from the Pliocene bed of the valley of 
Mexico, where it was abundant. The molar teeth are rather 
' "Proceed. Amer. Philosoph. Society," 1884, p. 5. 
