AMERICAN ZOOLOGISTS AND EVOLUTION. 185 



ous other memoirs from which may be gathered the author's views 

 on the subject. The essays of Prof. Hyatt, " On the Parallelism be- 

 tween the Different Stages of Life in the Individual and those in the 

 Entire Group of the Molluscan Order Tetrabranchiata," "Reversions 

 among Ammonites," " Evolution of the Arietidae," " Genetic Relations 

 of the Angulatidse," " Abstract of a Memoir on the Biological Rela- 

 tions of the Jurassic Ammonites," are altogether too technical to 

 condense into an address of this nature. It need hardly be mentioned 

 that in these memoirs invaluable contributions are made to the doc- 

 trines of natural selection. And now we come to the most difficult 

 part of our work : to compass within the limits of a few pages the mag- 

 nificent discoveries of Leidy, Marsh, and Cope, in the rich fossiliferous 

 beds of the West. The wonders are so unique and varied ; they have 

 been poured upon us with such prodigality of material and illustra- 

 tion, that one is baffled in an attempt to compass their characters, or 

 to picture them as realities. When Darwin offered the imperfection 

 of the geological record as possibly accounting for the absence of in- 

 termediate forms which might have existed, he was at once met by a 

 series of protests so strenuous, and at the same time so specious, that 

 they had their full weight in staying the force of that prophetic chap- 

 ter. Darwin, in this chapter, distinctly stated that n6t only were 

 there forms which had never yet been seen, owing to the imperfection 

 of the geological record, but that time might possibly bring them to 

 light, and, when discovered, we should have revealed to us interme- 

 diate characters which would connect widely-separated groups as 

 they are recognized to-day. 



Behold the prophet ! Animals have been discovered, not only 

 showing the characters of two widely-separated groups, but in some 

 cases of three groups as they now appear. How distinct the hoofed 

 quadrupeds, the carnivora, and the rodents, appear to-day ! Yet here 

 are discovered ancestors of these widely-separate groups, in which 

 are contained in one individual the characters of all three ! Of the 

 ungulates with the perissodactyle foot, there have been discovered a 

 large number of tapiroid forms allied to Paleotherium ; others which, 

 like Anchitherium, wonderfully fill the gap between the horse and 

 forms lower down ; a large suite of rhinocerotic creatures of strange 

 character and enormous size ; a great number of species of three- 

 toed horse, some no larger than foxes, and with these a perplexing 

 maze of deer, antelopes, sheep, camels, hippopotami, and pig-like ani- 

 mals, ruminant-like beasts, some of them not larger than an ordinary 

 squirrel: a curious group, comprising a large number of species with 

 characters intermediate between the pigs and ruminants. Prof. 

 Flower, the great English osteologist, confesses that these forms 

 completely break down the line of demarkation between them, and 

 adds that " a gradual modification can be traced in the characters 

 of the animals of this group, corresponding with their chronological 



