f34 
The American Naturalist. 
remarkable species occurs in the Plistocene beds of the east- 
ern region, the Cervalces americamis Harlan. Its affinities 
are with the Moose, with which it agrees nearly in size ; but 
it differs in possessing a posterior branch to the horn, which 
forms a broad, curved plate extending outwards above and 
behind the orbit, which resembles somewhat a hearing 
trumpet. 
Addendum. 
In the first part of this article in the NATURALIST for De- 
cember, 1888, p. 1088, I have given the characters of the sub- 
family, Dicotylinae, of the family Hippopotamidae, and of the 
two included genera, Dicotyles and Platygonus. Some 
amendment of these definitions is necessary, as follows : 
That of the sub-family " Digits three" should be supple- 
mented by the words, — on the anterior foot, and four on the 
posterior. The genera are both stated to have premolar 
teeth similar to the true molars. This statement must be 
qualified as regards the species now referred to Dicotyles, 
and must be contradicted as regards Platygonus. In the latter 
genus the deciduous premolars only resemble the true mo- 
lars (fig. 6, p. 1093), and they have the peculiarity of remain- 
ing in the jaw until the last true molar is nearly protruded. 
In Dicotyles, the deciduous teeth have disappeared before 
the last true molar is protruded. The permanent premolars 
are, as Leidy has described them, generally simpler than the 
true molars, consisting of two external, and one internal 
But the species differ so much in the characters of their pre- 
molars that they can be referred to three subdivisions, which 
may be at some future time regarded as genera. These are as 
follows : 
I. Premolars all different from molars {Notophortis Gray) ; 
D. tajassus. 
II. Last premolar only, like the molars {Dicotyles Cuv.) ; 
D. labiatus Cuv. ; D. serus Cope ; D. angulatus Cope.' 
III. Second premolar (from front) like true molars {Mylo- 
hyus Cope) ; D. nasiitus Leidy. 
It is uncertain whether the complex premolar oi D. nasutus 
I American Naturalist, Feb. 1889. 
