HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 203 
characters which appear to justify the erection for these genera of a subfamily in 
addition to the entire absence of the first and fifth digits, are the following: (1) in 
Macrotherium, and presumably in the other genera the astragalus articulates with 
both the cuboid and the navicular, a distinctively perissodactyl feature; (2) the 
hind limb in Macrotherium is relatively much shorter than the fore limb; (3) so far 
as is known, all of these genera are characterized by a noticeable shortening of 
the muzzle, through a reduction in the length of the premaxillaries and the anterior 
portion of the mandible. 
While we feel justified in erecting the foregoing subfamilies for the reception 
of the genera, which are the types of each, viz.: Schizotherium, Moropus, and Macyro- 
therium, it must be understood that the reference of the other genera which have 
been placed in these subfamilies is of necessity more or less provisional, because 
of the lack of material which would permit of more accurate determinations in 
some respects. Unfortunately our knowledge of some of these genera is very 
insufficient, they being in a number of cases merely represented by fragments 
which do not permit of exact comparisons between corresponding parts of the 
skeleton. We know enough, however, to be able to affirm with emphasis, that a 
distinct evolutionary process has taken place in these forms, and those from later 
geological horizons show marked differences in their anatomical structure from 
those derived from the earlier formations, differences so great as to fully justify 
their recognition in the manner we have adopted. 
CHAPTER II. THE GENERA OF THE CHALICOTHEROIDEA. 
Famity CHALICOTHERIID Gill. 
Subfamily SCHIZOTHERIINZ subfam. nov. 
Genus SCHIZOTHERIUM Gervais. 
Gervais, Zodlogie et Paléontologie Génerales, 2me Ser., Livr. iii, pp. 58-59 (1876). 
Synonym Limognitherium Filhol, Comptes Rendus, Vol. XC, p. 1580 (1880). 
Cf. Filhol, Ann. des Se. Nat., Vol. XVI, p. 145 (1894). 
Type: S. priscum (Gaudry). Comptes Rendus, Vol. LXXXI, pp. 1036-38 (1875); 
Journal de Zodlogie, Vol. IV, p. 519, 523, Pl. XVIII (1876); cf. Filhol, Ann. 
des Se. Nat., Vol. XVI, pp. 141-148 (1894). 
Type Specimens: A fragment of the left maxillary containing the premolars and 
the two anterior molars, metatarsals, metacarpals, phalanges. 
