152 The American Naturalist. [March, 
Founded on a mandibular symphysis and part of the left 
ramus of an adult animal, which contains the alveoli of the an- 
terior four molars, and part of that of the fifth. All the pre- 
molars are two-rooted, showing that they are but three in 
number. Canines and incisors wanting, the anterior alveolar 
margin thin and little prominent, and bilobed, with a median 
emargination. Symphysis coossified, with an angulate inferior 
margin, posteriorly with a fossa on each side of the median 
line, sloping regularly upwards to the alveolar margin, and 
concave above behind the margin. Minute traces of alveoli of 
a canine and two incisors on each side, which were probably 
present in the fcetus. Length of symphysis above, 120 mm.; 
depth posteriorly, 48 mm. Length of symphysis in front of 
p. m. iii. Length of premolar series, 75 mm. Length of m. i., 
40 mm. 
Although this is the first announcement of the discovery of 
the genus Chalicotherium in America, it is not the first discov- 
ery. Professor Scott showed me a series of superior molars 
from the Loup Fork formation of Kansas, from the Agassiz 
Museum, which he identified as belonging to this genus. The 
present species is of larger size than the Kansas form, and is 
apparently equal to the C. goldfussii of the Upper Mio- 
cene of Europe. The occurrence of this form in the Lower 
Miocene (White River), as well as the Upper Miocene (Loup 
Fork), of this country, is a noteworthy fact, but is parallel to 
its history in Europe. Described from the upper Miocene by 
Kaup, it was afterwards found in the middle Miocene {C. grande) 
by Lartet, and in the Upper Eocene {C. modicum), by Gaudry. 
The remarkable character of this genus, as discovered by 
Filhol, has been already mentioned in the Naturalist.' It 
has little relation to the family of Perissodactyla, to which it 
has given the name, and which it so resembles in molar denti- 
tion. It must form a family by itself, and the genera with 
which it has been associated must form a family to which the 
name Lambdotheriidas may be applied. The anterior ungual 
phalanges of Chalicotherium are of prehensile character and 
not ungulate, but rather unguiculate. The phalanges resem- 
ble those of the Edentata, but the carpus and tarsus are, 
according to Filhol, diplarthrous in structure, while the Eden- 
tata are taxeopodous. We have in the Chalicotheriidai the 
antithesis of the Condylarthra. While the latter is ungulate 
with an unguiculate carpus and tarsus, the former is unguicu- 
late with an ungulate (diplarthrous) carpus and tarsus. Thus 
1 Osborn on Chalicotherium, 1888, p. 728. 
