LAMBDOTHERIID^E, ETC. 413 



while there may be traces of an anterior ridge. The premolars 

 are simpler. 



Lambdotheriidce. This family is confined to the Upper Eocene 

 and Miocene of North America, where it is represented by Lambdo- 

 therium, Palceosyops, 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 loAver molar has a third lobe. Limnosyops differs from Palceosyops 

 in having two inner columns to the last upper molar. 



Chalicotheriidce. 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 vertebrae 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- 

 theriurn and Moropus. An- 

 cylotherium, of the Grecian 

 Pikermi beds, is founded upon 

 phalanges which indicate an F io. irs.-Anterior and distal aspects of 



allied genUS. The Indian phalangeal bone of Chalicotherium sivaknse. (From 



species of Chalicotherium is dis- the p <******* ^-> 



tinguished by the loss of the incisors and the upper canine ; while 



all the species want the first premolar. 



Titanotheriidce. This exclusively North American family in- 

 cludes gigantic forms closely allied to the Lambdotheriidce, 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, Titanotherium (Menodus, 1 Brontotherium, Symborodon, 

 Allops, etc.), may either have the full complement of teeth, or the 

 incisors may be reduced to . 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 Ehinoceroses ; 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. 



