426 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
lections, properly speaking, did not exist as yet. They were divided 
among various zoologists. It was not until seven years later (in 
1879) that Gaudry was able to gain possession of the fossils of 
Pikermi which he had collected and studied. The benevolent admin- 
istration of the museum permitted him to erect a little glazed shed. 
This, fortunately, was only intended as a means of obtaining a 
building more worthy of the paleontological riches which he wished 
to display and make known to all. But what a mass of persuasion 
was necessary in order to obtain a palace similar to that of zoology! 
When the exhibit was assembled and arranged according to his ideas, 
it appeared, to quote the eloquent words of M. Liard, “ like a history, 
like a philosophy. It is in effect the history of the animal creation, 
an interpretative history, rendered visible and tangible.” In this 
splendid exhibit of the recovered evidences of past ages, arranged 
according to their appearance on the globe, one has in brief the his- 
_ tory of the animal kingdom, from the radiolarians of the Cambrian 
formations up to the earliest of the human races, already the Homo 
sapiens. 
Before arriving at this last stage,Gaudry had brought together his 
ideas as investigator and professor in the form of treatises which 
have had a considerable fame. 
5. The links of the animal kingdom. The unity of plan of the animal 
kingdom. 
After six years of teaching Gaudry brought out his first volume 
on “ The links of the animal kingdom—Tertiary fossils” (Les E'n- 
chainements du monde animal. Fossiles tertiaires), a work whose 
suggestive title caused considerable enthusiasm among naturalists of 
all lands. 
Some years afterwards appeared the “ Primary fossils” and the 
“Secondary fossils.” This scientific trilogy summarized a great part 
of the work and ideas of Gaudry. The word links (enchatnements) 
reveals sufficiently the spirit which dominates it. .'There existed links, 
evident connections between the diverse beings which have appeared 
successively on the globe, and those which exist to-day. These last 
are merely the resultants, or the remainders, of an evolution of which 
the different steps are found in the geological series. The living 
world can be explained only through a knowledge of the worlds 
which have disappeared. There is not a fossil world and a living 
world, but a single world. If the evolution of different beings which 
from time to time have inhabited the earth has proceeded under the 
action of natural causes (modifications due to the environment, to 
wants, to migrations, to mutations, ete.), it appeared to Gaudry that 
“the causes themselves must operate for the realization of a plan, 
