LAMBDOTHERIHDA, ETC. . 413 
while there may be traces of an anterior ridge. The premolars 
are simpler. 
Lambdotheriide.—This family is confined to the Upper Eocene 
and Miocene of North America, where it is represented by Lambdo- 
therium, Paleosyops, and Limnosyops ; it presents the normal type 
of foot structure, and all the genera except the first have the full 
complement of teeth. There were four digits in the manus. The 
last lower molar has a third lobe. Limnosyops differs from Paleosyops 
in having two inner columns to the last upper molar. 
Chalicotheriide.—The genus Chalicotherium, which is found in the 
Tertiaries of Europe, Asia, and North America, differs so remark- 
ably in the structure of the feet from all other Ungulates that it has 
been proposed to regard it as the representative of a distinct order, 
Ancylopoda. The molars are, however, almost indistinguishable 
from those of the preceding and following families ; while the cervi- 
cal vertebree and portions of the limbs are of a Perissodactyle type. 
On the other hand, the femur has lost its third trochanter ; while 
the phalanges are strangely modified, the terminal ones forming 
long curved claws, while the others > (Fig, 175) have strong ging- 
lymoid distal articulations. 
These phalanges were, indeed, 
long regarded as referable to 
Edentates, being described in 
Europe as Macrotherium, and 
in the United States as Moro- 
therium and Moropus.  An- 
cylotherium, of the Grecian 
Pikermi beds, is founded upon y 
phalanges which indicate an 1G. 175.—Anterior and distal aspects of a 
allied genus. The Indian phalangeal bone of Chalicotherium sivalense. (From 
species of Chalicotherium is dis- ‘® Pwontolegia Indica.) 
tinguished by the loss of the incisors and the upper canine; while 
all the species want the first premolar. 
Titanothertide.—This exclusively North American family in- 
cludes gigantic forms closely allied to the Lambdotheriide, but with 
the last upper premolar as complex as the molars, and frequently 
with large bony protuberances in the nasal region. The best 
known genus, Titanotheriwum (Menodus, Brontotheriwm, Symborodon, 
Allops, etc.), may either have the full complement of teeth, or the 
incisors may be reduced to #2. The canines and incisors are small, 
and there is no diastema when the full dental series is developed. 
The skull is very like that of the Rhinoceroses; but has a trans- 
verse pair of large bony prominences on the nasal region, varying 
considerably in shape and size in the different species, which in the 
living animal were probably covered with horny sheaths. The third 
1 This name is the earliest, but is preoccupied. 
