244 The American Naturalist. [Mareh, 
Length of horn beyond termination of nasals 
Diameter of horn 041 
Length of molar dentition 158. 
Greatest transverse diameter of molar two 069 
Greatest antero-posterior diameter of molar two 
LOWER JAW AND TEETH. 
Length of ramus from anterior border of premolar four to 
posterior border 420 
Height from bottom of angle to condyle - -260 
Depth below molar three 109 
Length of molar dentition 155. 
Length of molar two 054 
Length of molar three hi 
Teleoceras although presenting several characters appal 
ently intermediate between Aphelops and existing genera ji 
Rhinoceridæ, nevertheless cannot be considered as an ancestor 
of the latter. Neither is it a migrant from Europe. Ka 
really a horned Aphelops derived perhaps through Leidy’ S 
Species A. crassus; which latter is not unlikely to be identical 
with A. fossiger (Cope) and A. acutum (Marsh), all of whi j 
have been described as possessing compressed, acuminate 
nasals, thus suggesting a horn at the very place where it 
appears in Teleoceras. w 
The discovery of a median horned Rhinoceras in America 18 
of interest not as a probable ancestor of existing Old we 
forms, but rather as exhibiting a remarkable example 
parallelism in the development of the Old and New Wot 
_ Species of Rhinoceride from their common ancestral genus 
Aceratherium of the lower Miocene of this continent. ee 
present knowledge would indicate, as has been pointed out 9Y 
Scott,’ that the ancestral type originated in America and foun 
its way into the Old World in early Miocene times. These — 
nus Aceratherium which flourished during the lower M pe = 
was common to both continents, and all the median ho 
*See Bull. 3, E. M. Museum, Princ. Coll., pp. 1-22, 1883. 
