PALEONTOLOGY 299 



the earth's early days and calling tlioiii to life aj^aiii, and in our imagina- 

 tion we ask these ancient inhabitants of the earth whence they were 

 derived : 'Speak to us and say whether you are isolated remnants 

 disseminated here and there throughout the inmiensity of the ages, 

 without order more comprehensible to us than the scattering of flowers 

 over the prairie? Or are you in verity linked one to another so that 

 we may yet be able amid the diversity of nature to discover the in- 

 dications of a plan wherein the Infinite has stamped the impression of 

 His unity?' The unraveling of the ])lan of creation — this is the goal 

 to which our efforts now aspire. Whatever our theories, as to it," 

 Gaudry continues, "there is a plan. A day will come when the 

 paleontologists will seize the i^lan which has presided over the de- 

 velopment of life." 



This plan is found in the phenomena of organic evolution, 

 the interrelation of the different factors or forces of heredity, 

 variation, adaptation, fecundity, with the conditions of isola- 

 tion of forms and the relations of environment. In the study 

 of these details, we receive great light from the investigation 

 of comparative structure, and the forces and processes of 

 individual development. These are Haeckel's ancestral docu- 

 ments of morphology and embryology, but all theory finds its 

 final verification in its accord with the facts of paleontology, 

 the recorded evidence of succession in time. 



Among the general deductions from paleontology are the 

 following : 



The various primary groups or branches of the animal 

 kingdom as well as the principal classes are all very old, most 

 of them, the vertebrates excepted, appearing in the earliest 

 known fossiliferous rocks. It is, however, evident that these 

 rocks. Lower Silurian or Ordovician and Cambrian, are very 

 far from the actual beginning of life. 



In each group the earliest forms are relatively simj^le, 

 unspecialized, and as a rule marine. Many of them are em- 

 br3^onic types, that is, forms morphologically comparable to 

 the embryos of forms of later a})pearance. To such forms, 

 the less appropriate term of "prophetic types" has been ap- 

 plied. Many of the earher forms are of synthetic types, 

 that is, embracing characters distinctive of different diver- 

 gent groups. Such synthetic typ(*s, where the resemblances 

 are shown to be indicative of real homologv, are now rc^- 



