i 9 4 TEE POPULAR SCIENCE MONTHLY. 



that " the mammals of the Lower Eocene exhibit a greater percentage 

 of types that walk on the soles of their feet, while the successive pe- 

 riods exhibit an increasing number of those that walk on the toes ; 

 while the hoofed animals and Carnivora of recent times nearly all 

 have the heel high in the air, the principal exceptions being the ele- 

 phant and bear families." After presenting the gradual osteological 

 changes of the foot, from the earlier types to the later ones, through 

 several lines of descent, considering also the teeth as well, he says : 

 " The relation of man to this history is highly interesting. Thus, in 

 all generalized points, his limbs are those of the primitive type, so 

 common in the Eocene. He is plantigrade, has five toes, separated 

 tarsals and carpals, short heel, rather flat astragalus, and neither hoofs 

 nor claws, but something between the two ; the bones of the foreai'm 

 and leg are not so unequal as in the higher types, and remain entirely 

 distinct from each other, and the ankle-joint is not so perfect as in 

 many of them. In his teeth his character is thoroughly primitive. . . . 



"His structural superiority consists solely in the complexity and 

 size of his brain. A very important lesson is derived from these and 

 kindred facts. The monkeys were anticipated in the greater fields of 

 the world's activity by more powerful rivals. The ancestors of the 

 ungulates held the fields and the swamps, and the Carnivora, driven 

 by hunger, learned the arts and cruelties of the chase. The weaker 

 ancestors of the Quadrumana possessed neither speed nor weapons of 

 offense and defense, and nothing but an arboreal life was left them, 

 where they developed the prehensile powers of the feet. Their di- 

 gestive system unspecialized, their food various, their life the price of 

 ceaseless vigilance, no wonder that their inquisitiveness and wakeful- 

 ness were stimulated and developed, which is the condition of progres- 

 sive intelligence " adding that " the race has not been to the swift, 

 nor the battle to the strong." Prof. Cope shows in this case that 

 " the survival of the fittest has been the survival of the most intelli- 

 gent, and natural selection proves to be, in its highest animal phase, 

 intelligent selection." 



Prof. Fiske has in a clearer way shown that when variations in 

 intelligence became more important than variations in physical 

 structure, then they were seized upon, to the relative exclusion of the 

 latter. 



It is intelligent strength, other things being equal, that conquers 

 the savage, and the gradual selection of the best and biggest brains 

 is not seen alone in man. 



In one of the most significant discoveries of Prof. Marsh, the mam- 

 malia are found to show an increase in the size of the brain coincident 

 with their succession in the rocks. 



One of the most extraordinary mammals from the Tertiary beds 

 of the West is the Dinoceras, with its rhinoceros and elephant char- 

 acters, its skull ornamented with prominent tubercles, its unique den- 



