COPE.] PALEONTOLOGY MIOCENE PERIOD. 483 



of that order. The scapular aud pelvic arches have the same significance 

 iu the gradually-desceuding spiue of the former and pedunculate ilium 

 of the latter. Tbe limbs testify to the same effect, and in the third trochan- 

 ter of the femur, (small, it is true,) the digitigrade hindfoot, with attend- 

 ant modifications of the structure of the calcaneum aud astragalus. 

 Its only indications of other affinity are a few toward the UohasUeidm, 

 seen iu the enlarged cuboid facet of the astrag.dus, the elongate femur 

 with reduced third trochanter, and the iiaired horns on the anterior part 

 of tbe cranium. They present no special marks of affinity to the artio- 

 daetyles, and show that the paired horns of the Eohasileidce have no 

 significance iu the same direction, as has been supposed by a recent 

 writer on this group. 



As compared with the EJiinoceridce, the principal distinctions are to 

 be observed in the feet, iu which the median i^air of toes are less un- 

 equal in proportions. The cranium is still more abbreviated in front 

 and the orbits more anterior, while the bilateral arrangement of horns 

 belongs exclusively to the extinct. The structure of the molar teeth is 

 distinct, but not widely so, and represents a more primitive type, and 

 one approximating the bunodont forms of Prohoscidia and Artiodactyla., 

 and lower types. The same type of detention is displayed by Palasyops, 

 Leidy, of the American Eocene ; Chalicotherium,* Kaup, of the Miocene 

 of Europe and Asia; and Titanotherium, Leidy, of the American Miocene. 

 It is with the latter genus that comparisons must now be made. 



Titanotherium 'proutii, Leidy, is a large species, originally described 

 by Dr. Hiram Prout in the American Journal of Science and Arts t as d 

 Palceotheriuni. It was based on specimens brought by Dr. Prout from 

 the Missouri. Subsequently, Messrs. Owen, ll^Torwood, and Evans named 

 it Palcmtherium% Proutii^X they had procured other material, but 

 based their name on Prout's descriptions. In the same year. Dr. Leidy 

 proposed for it the generic naaie Titanotherium,^ without generic de- 

 scrij)tion or diagnosis. In his work on The Ancient Fau.ua of E"ebraska,|| 

 Dr. Leidy gave a full specific description of the materitd which had 

 been obtained up to that time, and it is on this and the figures accom- 

 panying that our linosvledge of Titanotherium as o, ge^as reposes. Iu 

 the Journal of the Philadelphia Academy,^ 1869, Dr. Leidy had de- 

 scribed additional remains, chiefly cranial, some of which belong to dif- 

 ferent species, and perhai)S some of it to those of the present allied 

 genus. 



Doctor Leidy gives the dental formula of Titanotherium, as L, 2 ; C, 

 1; P. m., 4; M., 3, for the maxillary series, and adds:** ''Fragments of 

 lower jaws exhibit the same number of molar and canine teeth, aud 

 probably there existed also the same number of incisors as in the 

 upjier jaw." In the museum of the Academy of Natural Sciences, one 

 of Dr. Prout's original specimens, as indicated by the label and the one 

 first figured by Dr. Leidy, is preserved, but it furnishes no evidence as 

 to the number of premolars. Associated with it in the collection is a 

 mandibular symphysis, tf marked as being one of Dr. Owen's original 

 specimens. These two are j)eculiar in their iron-rust color, so different 

 from that always characterizing the fossils of the White River epoch 



'Professor Gill has created a family, Challcotheriidw, for this genus. 



t II, 288, fig. 1, 184G ; III, 248, figures, 1847. 



t Proceed. Acad. Nat. Scieuces, 1850, 6G. 



$ Proceed. Acad. Nat. Sciences, ISriO, 122. 



II Smithsonian Coutrib. to Knowledge, vol. VI. 



11 Extinct Fauna Dakota and Nebraska, 1869, p. 206. 



** Page 207. 



ft Described by Leidy in his Fauna Dakota aud Nebraska, p. 214. 



