256 Bulletin American Museum of Natural History. [Vol. XIII, 



enamel thin ; protocone large, strongly constricted off. These 

 dental characters approach those of Teleoceras fossiger. 



In some of its cranial characters 



crochet /■rltia 



it approaches A. incisivum, except in 

 the extraordinarily broad chin which 

 is hollowed out in the median line 

 (see also lower jaws referred to A. 

 ^^j^^.^^^ ^^ blanfordi in British Museum) ; thus 



, , . the lower canines diverge and are set 



rig. 12a. Aceratkerium persiip. ° 



Second and third superior molars, widely apart, with the persistent alve- 



Halle. 



oli of lower incisors between ; nasals 

 short, straight and smooth ; a sagittal crest ; occiput higher 

 than broad ; zygomatic arch slender. A strong rugosity upon the 

 molars beneath the eyes for the origin of the masseter muscles, 

 which are inserted in a strong ridge on the outer border of the 

 angle of the jaw. Tibia and fibula closely united (as .in Brachy- 

 podinae). Limbs of medium length. 



Subfamily CERATORHIN^. PHYLUM IV. 



Middle Miocene to recent Rhinoceroses ; dolichocephalic, ivith frontal horns, 

 and nasal horns upon a distinct mid-nasal convexity, not terminal ; nasals more 

 or less pointed and recurved anteriorly ; cutting teeth large in early members, 

 gradually reduced in certain brajich phyla ; cursorial limbs. 



The first known of this series, R. sa?isaniensis of the Middle 

 Miocene, appears to represent a new arrival and a new phylum in 

 Europe ; it certainly has no ancestors among the previously 

 known Diceratheriinse, Brachypodinae, or Aceratheriinae, for the 

 structure of the entire upper portion of the skull is different ; it 

 is barely possible that some of the teeth referred to A. mitiutum 

 from the Upper Oligocene may represent its ancestors ; but 

 this is not probable. Its successors or collateral descend- 

 ants, however, are probably determined as the R. simorrensis of 

 Simorre, the R. steinheiinensis of the Upper Miocene of Steinheim 

 and Grive-St.-Alban ; these animals apparently gave off : (^) a 

 smaller race., the last of which appears in the Lower Pliocene, Ep- 

 pelsheim ; in Eppelsheim and Pikermi, however, there also ap- 

 pears (^) the larger race of R. schleier7nacheri possessing many of 

 the same characters as R. sansaniensis, but with certain notable 

 distinctions. 



