IX, 
EVOLUTION OF FOSSIL CEPHALOPODA. 
By JAMES PERRIN SMITH. 
Most of the paleontologic contributions to the evi- 
dence of evolution were gathered before the time of 
Darwin, and are therefore all the more 
trustworthy because the naturalists that 
gathered them were not evolutionists. 
It is indeed remarkable that their classifications have 
been so little changed by the introduction of the theory 
of evolution into the study of biology. Since this is the 
case the paleontologic record ought to show the order 
of appearance of genera in time, and their genetic rela- 
tionship. It does do this in a general way. Thus in 
the echinoderms we have the cystoids, apparently the 
primitive stock, beginning in the Cambrian and disap- 
pearing in the Carboniferous; the blastoids, somewhat 
higher, began in the Upper Silurian and disappeared in 
the Carboniferous; the true crinoids, or sea lilies, began 
in the Lower Silurian and survived until the present day. 
Asteroids we know from the Cambrian on, and echinoids, 
or sea urchins, from the Lower Silurian until now. 
Although their succession in time suggests genetic 
relationships, the crinoids, and especially the cystoids, 
being the most primitive type, the first known of the 
three great groups are apparently as widely separated 
from each other as they now are. Either they are par- 
229 
General evidence 
of paleontology. 
