114 SYNOPSIS. 



ORDINARIA. 



ARCH AEOTHERIUM. With a sagittal crest ; orbits closed by a post-orbital arch ; glenoid arti- 

 culation transverse. Lower jaw with a basal apophysis as in Anthracothen'um. Dental formula : 



• ? — ? 1?— 1? 4?— 4? 3—3 ^ „ , , 1 * vT. * X 



m. c. — p.m. —- — — - m. -. Crowns of upper true molars quadrate, with two trans- 

 verse rows of three conical tubercles or lobes ; the lower ones with two transverse pairs of tubercles, of 

 which that antero-intcrnally is subdivided. Last upper premolar bilobed; penultimate upper molar com- 

 pressed conoidal. Last lower premolar compressed conoidal. 



1. Archaeotheriuji Mortoni. Head about the size of that of the Lion. 



2. Arciiaeotherium robustum. Rather larger than the preceding. 



UNGULATA IMPARIDIGIT AT A. 



SOLIPEDIA. 

 ANCHITHERIUM. With a short sagittal crest; forehead broad and large; orbits large. Dental 



formula: in. c. m. Molars constructed after the type of those of Palaeotherium. 



3 — 3 1 — 1 7 — 7 



Anchitherium Bairdii. About the size of Anchlthcrium aurelianense. 



ORDINARIA. 



TITANOTHERIUM. Dental formula as in Palaeotherium ? Upper molars quadrate, complex, inter- 

 mediate in form to those of Palaeotherium and Rhinoceros; their outer side without the double arched 

 ridge characteristic of the former, and without the anterior marginal fold characteristic of the latter. 

 Lower molars like those of Palaeotherium, but possessing no inner basal ridge. 



TiTANOTHERiUM Proutii. Unique species. 



PALAEOTHERIUM. Dental formula : in. ?-=-? c. l^^ p.m. 1=1^ m. ?^^ = 44. Upper 



3 — 3 1 — l'^ 4 — 4 3 — 3 ^^ 



molars quadrate, complex ; with an external double-arched ridge. Lower molars bilunate; the last trilunate. 

 Palaeotherium giganteum. Twice the size of the Palaeotherium magnum ; being the largest spe- 

 cies of the genus. 



RHINOCEROS. With a nasal or frontal horn, or both, or none. Dental formula : in. , or 



— 

 1 — 1 2 — 2 — 7 — 7 , ,.,,.. 



, -. ) or .^ .^ '^- f. » '"'■ ■- .-■ Upper molars quadrate, complex; with a characteristic antero- 



external fold. Inferior molars composed of a pair of right angled crescentoid lobes. 



1. Rhinoceros occidentalis. With a sagittal crest; frontal horn none; nasal horn? forehead 

 broad and flat. Three-fourths the size of Rhinoceros indicus. 



2. Rhinoceros Nebrascensis. With a sagittal crest; frontal horn none; nasal horn? Three- 

 fourths the size of Rhinoceros occidentalis. 



