INTRODUCTION 7 



memoirs of Wilhelm Heinrich Waagen in 1869. Phyletic or ancestral 

 gaps began to be filled in a general way, however, especially through re- 

 markable discoveries in North America by Leidy, Cope, and Marsh; and 

 the ensuing phylogenies, or ' trees, ' of animal descent gave enormous pres- 

 tige to palaeontology, as affording the most convincing proofs of evolution. 



Primitive and progressive stages. — It was early (1870-1873) observed 

 by Huxley, Cope, and others that Cuvier's broad belief in a universal law 

 of perfection was erroneous, and they began to perceive the difference 

 between persistent primitive types (Huxley) and progressive or 

 advancing types. Darwin himself had anticipated that primitive 

 or stem forms of the existing modernized or specialized kinds of animals 

 would be discovered. The analytic steps by which from existing knowl- 

 edge the stem form might be reconstructed before its discovery, were first 

 fully and clearly described by Huxley in 1880,^ namely, by separating all 

 the specialized, or modern, characters of mammals from all the primitive, 

 or original and simple characters, and by putting together the latter to 

 compose an ancestral or stem form of mammal. Thus, more or less inde- 

 pendently, Huxley, Kowalevsky, and Cope had ventured to picture what 

 the ancestor of the hoofed mammals, or ungulates, would be like when 

 discovered, namely, an animal whose chief characters would be grinding 

 teeth with simple, rounded cusps, and feet with five separate and com- 

 plete digits. This prophecy and restoration at first seemed to have been 

 entirely realized and fulfilled in the discovery in northern Wyoming, in 

 1873, of a generalized hoofed mammal, to which Cope gave the name 

 Phenacodus, although this mammal has since proved not to be directly 

 ancestral to any form, but rather to stand for a type. 



The reconstruction of primitive ancestral forms was so much more 

 facile and enjoyable than the arduous labor of exploration and research 

 that it naturally went to extremes. Here we are reminded of a critical 

 saying of the late Professor von Gudden, the distinguished neurologist 

 of Munich: " Ein Steinchen der Wahrheit hat mehr Werth als ein grosser 

 Schwindelbau." In palaeontology the great " Schivindelbau," literally 

 "the false structure," is the phyletic tree, which adorns the end of many 

 good as well as many superficial papers. Recently, because of their (ex- 

 tremely brief existence, these phylogenies have fallen somewhat into dis- 

 favor, yet the present reaction against these trees does not seem to be 

 altogether wise, for we must remember that they are among the working 

 hypotheses of this science, which serve to express most clearly the 

 author's meaning. 



Precise and philosophical research. — The first twenty years after the 

 publication of Darwin's "Origin" will always remain a golden era in the 



' Huxley, On the Application of the Laws of Evolution to the Arrangement of the Ver- 

 tebrata and more Particularly of the Mammalia. Proc. Zool. Soc, London, 1880, pp. 649-662; 

 Scientific Memoirs, Vol. IV, pp. 457-472. 



