FOSSIL PEDIGREES 117 



letic evolution in particular. All the great invertebrate types, 

 such as the protozoa, the annelida, the brachiopoda, and large 

 crustaceans called eurypterids, are found in rocks of the Pro- 

 terozoic group, despite the damaged condition of the Archaean 

 record, while in the Cambrian they are represented by a great 

 profusion of forms. "The Lower Cambrian species," says 

 Dana, "have not the simplicity of structure that would natur- 

 ally be looked for in the earliest Palaeozoic life. They are per- 

 fect of their kind and highly specialized structures. No steps 

 from simple kinds leading up to them have been discovered; 

 no line from the protozoans up to corals, echinoderms, or 

 worms, or from either of these groups up to brachiopods, mol- 

 lusks, trilobites, or other crustaceans. This appearance of 

 abruptness in the introduction of Cambrian life is one of the 

 striking facts made known by geology." ("Manual," p. 487.) 

 Thus, as we go backward in time, we find the great organic 

 phyla retaining their identity and showing no tendency to 

 converge towards a common origin in one or a few ancestral 

 types. For this reason, as we shall see presently, geologists 

 are beginning to relegate the evolutionary process to unknown 

 depths below the explored portion of the "geological column." 

 What may lurk in these unfathomed profundities, it is, of 

 course, impossible to say, but, if we are to judge by that part 

 of the column which is actually exposed to view, there is no 

 indication whatever of a steady progression from lower, to 

 higher, degrees of organization, and it takes all the imper- 

 turbable idealism of a scientific doctrinaire to discern in 

 such random, abrupt, and unrelated "origins" any evidence of 

 what Blackwelder styles "a slow ^Dut steady increase in com- 

 plexity of structure and in function." {Science, Jan. 27, 1922, 

 p. 90.) 



But, while the permanence of phyletic types excludes prog- 

 ress, that of generic and specific types excludes change, and 

 hence it is in the latter phenomenon, especially, that the theory 

 of transformism encounters a formidable difiiculty. Palaeo- 

 botany furnishes numerous examples of the persistence of \m- 



