254 The American Naturalist. [April, 
These bones do not resemble in color those from near Sil- 
ver Lake, Oregon, which are black. They are yellowish brown 
or light brown, like those from the locality in Whitman Co., 
which were recorded in the last number of the NATURALIST. 
The interest of the list consists in the fact, that it represents 
the first time a fauna which contains at the same time the 
large true horses and lamas, and the three-toed horses and 
Aphelops rhinoceros. The latter forms belong to the Loup 
Fork horizon, and the former to the Pliocene, and they have 
not been found hitherto in association in the Rocky Mountain 
Region. The fauna described from Florida, by Leidy, is 
probably of Loup Fork or Upper Miocene age, and the mam- 
malia are similar to or identical with those of the same horizon 
in Kansas and Nebraska. 
This fauna represents an older period than the Upper Plio- 
cene of Silver Lake, and may be, very probably, the contem- 
porary of that of the Pliocene lake of Idaho, from which I have 
described numerous species of fresh-water fishes. The de- 
posits containing them I called the Idaho beds (Proceedings 
Academy Philadelphia, 1883 p. 153), and they may be re- 
garded as representing the middle or lower Pliocene. The 
new Hippotherium is characterized as follows : 
Represented by two superior and three inferior molar teeth. 
The grinding surface is nearly square, and the crown is short, 
and moderately curved. The section of the internal style is a 
wide oval, and it presents no angle or point of approximation 
to the protoconic crescent, and conversely none to the poste- 
rior column. The latter has the usual connection with the 
hypoconic crescent, but projects as far inwards as the anterior 
area, and is well defined. The enamel-boundaries are quite 
simple. The usual loop of the posterior inner border of the 
anterior lake is rudimental in an anterior true molar, and in 
the last molar it is small and subround. No isolated loop. A 
single short process of the border towards the internal column. 
Cementum abundant. 
Dimensions of superior molars. No. i ; diameters of grind- 
face ; transverse, 19 mm.; anteroposterior, 16 mm. No. 2; 
transverse, 19 mm. ; anteroposterior, 18 mm. — E. D. Cope. 
Storms on the Adhesive Disk of Echeneis. — In a 
paper published in the Annals and Magazine of Natural His- 
tory for July, 1883, Mr. Storms endeavors to solve the different 
questions pertaining to the structure and morphological inter- 
