366 



PALEONTOLOGY. 



Fig. 127. 



Upper molar, Palceotherium magnum 

 (Eocene). 



a nearly complete skeleton. The fossils have been obtained 

 chiefly from the upper eocene gypseous formation at Mont- 

 martre and other parts of France. Though the molar teeth of 

 Palceotherium (fig. 127) resemble in shape and the pattern 



of the grinding surface those 

 of the rhinoceros (fig. 148), 

 the entire dentition in the 

 number, kind, and general 

 arrangement of the teeth, 

 agrees with that of Pliolophus. 

 The skull affords indications 

 that the Palseothere possessed 

 a short proboscis. It had 

 three toes on each foot, each 

 terminated by a hoof ; the 

 middle one being the largest. 

 The femur had a third trochanter, and the dorso-lumbar verte- 

 bras were 21 in number. Several species of Palceotherium 

 have been determined, ranging from the size of a sheep (P. 

 curtum) to that of a horse (P. magnum). Fig. 127 gives the 

 grinding surface of an upper molar of this species from the 

 upper eocene of the Bembridge beds, Isle of Wight. The 

 crown is divided into an anterior (/, \ d) and posterior (/, a, c) 

 part by an oblique fissure (e), continued from near the middle 

 of the inner surface of the crown obliquely across two- 

 thirds of the tooth. Each division is subdivided partially 

 into outer (a, b) and inner (c, d) lobes ; the anterior division, 

 by the terminal expansion (i) of the fissure (e), the posterior 

 one by the fissure (g). The lobes (c and d) are bordered near 

 their base by a ridge. This is the type of grinding surface, 

 on which are superinduced the modifications of that surface 

 in the upper molars of the rhinoceros and horse. The dental 

 formula of Palceotherium is * g-^J, c ^, p |^J, m |^j=44. The 

 canines exceed in length the other teeth, and there are con- 



