1LAJJ<^SJL.S CITY 



Review of Science and Industry, 



A MONTHLY RECORD OF PROGRESS IN 



SCIENCE, MECHANIC ARTS AND LITERATURE. 



VOL. VI. 



JUNE, 1882. 



NO. 2. 



PALEONTOLOGY. 



ON THE ORIGIN AND DEVELOPMENT OF THE EXISTING 



HORSES. 



BY JACOB L. WORTMAN. 



{^Contijiued from page "^26, Vol. K) 



The genus Hyracotherium, Owen, presents us with the next step in the direct 



line of ancestry. The dental formula is the same as in Phenacodus. A superior 



molar, Fig. 4,* shows the elements as seen in the corresponding tooth of Phena- 



r ^^2^5 with the exception of the external ribjv. A small fold of enamel at this 



I-IG. 7. 

 Fie;. 7. — -Skull of Hyracotherium venticolum. Cope. One-half natural sLie, after Cojsc, 



* i^age 725, Vol. V. 

 VI— 5 



