AMERICAN ZOOLOGISTS AND EVOLUTION. 187 



It is impossible for me to more than allude to these remarkable 

 additions to our knowledge of these early forms, and until tbey have 

 all been figured with natural outlines, and perplexing questions as to 

 priority in discovery rectified, it will be difficult in some cases to ac- 

 credit individual work. But in the light of these profound revela- 

 tions, how blind seem the attempts to establish a classification on the 

 forms heretofore familiar to us, and to rear these into circumscribed 

 groups between which it was asserted no forms of intermediate kinds 

 were to be expected ! "With the twenty-five or thirty species of fossil 

 horses at our command, some with four toes, others with three, in 

 various stages of reduction, it is interesting to bring back to mind 

 the earnest Geoffroy St.-Hilaire painfully endeavoring to trace the 

 genealogy of the horse, with a few widely-separated forms of extinct 

 mammals as his only guide in the work. 



The special investigations of Marsh and Leidy reveal an almost 

 unbroken line from our present horse with its simple toe, and two 

 rudimentary metatarsals in the shape of the splint-bones, to a creature 

 in which metatarsals support rudimentary toes, and still other forms 

 in which these rudimentary toes are working-toes, and below that 

 again another form in which a fourth toe is seen as a rudiment, till 

 forms are reached in which all the toes rest on the ground. It is still 

 more striking to study attentively those earlier generalized horses 

 with four toes, and follow the successive reduction in the number of 

 toes as the later formations are reached, till in the latest deposits and 

 at present we have the modern specialized horse with but a single 

 toe, the lost toes represented by two slender bones hidden beneath 

 the flesh. And now comes crowning proof that our modern horse has 

 been derived from some three-toed px-ogenitor, for in certain instances 

 horses have come into existence with splint-bones developed into sturdy 

 bones sustaining at the extremities phalangeal bones, and outside ac- 

 cessory hoofs ! Such freaks of Nature demand an explanation. They 

 receive a rational one through the theories of Darwin. Without the 

 law of reversion, we are left in blind bewilderment. 



While all these facts in overwhelming array testify to the extreme 

 mutability of forms, induced oftentimes by apparently the most triv- 

 ial of causes, and set at rest the question as to the fixedness of spe- 

 cies, they show at the same time the richness of that store from which 

 by natural selection forms may be selected. 



Realizing the uniformity of Nature's laws, the human mind 

 bravely asks, " Do these wonderful interpretations throw any light 

 upon the origin of man ? " 



Rigidly adhering to the inductive method, science is prepared to 

 show that man did not appear suddenly and free from those animal 

 proclivities and passions which make him a sinful creature, but that 

 he has risen from a lowly origin, and his passions and desires, but 

 feebly repressed, may be as surely traced to ancestral traits, as the 



