GAUDRY AND EVOLUTION—GLANGEAUD. 419 
needs of geology, in the examination of sedimentary deposits. Thus 
has taken birth from Cuvier and d’Orbigny stratigraphic paleon- 
tology, the sister of zoology and the essential basis of all rational 
geology. 
We recall in passing that d’Orbigny had divided the earth into 
twenty-seven epochs, among which he distributed the 18,000 known 
mollusks and echinoderms. The broad lines of the classification of 
this naturalist are still followed to-day. Cuvier and d’Orbigny 
believed that they had established by their works the fixity of 
species, and their sudden appearance and disappearance in time, due 
to successive cataclysms and creations. 
II. GEOFFROY ST. HILAIRE AND LAMARCK. 
Two of their contemporaries, Lamarck and Geoffroy St. Hilaire, 
arrayed against this “theory of the absolute ” another theory, which 
was destined henceforth to agitate the minds of all learned and 
thinking men. From this time, and arrayed around these natural- 
ists, were waged, under the banner of “ transformism,” innumerable 
scientific and philosophical battles. After a century of study and 
research the discussion still remains open on many points. 
Lamarck and Geoffroy St. Hilaire, contrary to Cuvier, d’Orbigny, 
and Brongniart, planting themselves on the study of living and 
fossil forms, claimed that there was no sharp separation between 
these different organisms, but that a filiation existed between them. 
The first animals which appeared were “ transformed ” successively 
under different influences, leading, under the influence of needs or 
habits (Lamarck), or under those of the environment (G. St. Hilaire), 
to the development or atrophy of certain organs. It was no longer 
held that there were successive creations, but rather that nature had 
produced at first simple organisms, which little by little, under in- 
fluences of which we shall speak presently, were modified, trans- 
formed into beings arranged in series more and more complicated, 
more and more nearly perfect, from the amorphous, gelatinous, but 
living, mass of the protozoan to man. 
Lamarck, in his Zoological Philosophy, in which, unfortunately, 
paleontological data played but a small part, prepared a genealog- 
ical tree of all forms of animals, from the simplest to the highest 
mammals (man excepted). This essay in comprehensive synthesis 
is interesting only on account of its spirit and the ideas on which 
it is based. It is inexact in a very great number of essential points, 
but it is the original foundation on which later naturalists have 
erected more precise ideas, having for a basis a larger number of 
observations. It was, furthermore, difficult for Lamarck to produce 
other than a preliminary work. He lacked the knowledge of a large 
