204 University of California Publications in Zoology (Vou. 9 
species lives along the whole western coast of North America 
from Panama at the south to Unalaska at the north. This is 
certainly a remarkable case of the adaptation of the same species 
to a great variety of environmental conditions. 
Although the extensive study of Jennings (1907) falls prop- 
erly under the heading of animal behavior, noticed later, the 
question of adaptiveness of this behavior to natural conditions 
under which the animal lives, received considerable attention. 
The results bearing on this may be summarized by saying that 
of the large number of reactions and activities of the starfish 
studied, every one is probably to some extent advantageous to 
the individual animal. At least it is not suggested that any 
activity studied is without significance for some particular aspect 
of the creature’s existence. 
(e) The Doctrine of Natural Selection 
Kofoid (1906c) and Ritter (1909b) have dealt specifically 
with this subject to some extent. 
Studying the species-characters of the dinoflagellate already 
referred to, Kofoid concludes that ‘‘in assigning natural selec- 
tion as the cause of the species characters in Triposolenia we are 
at once confronted by the difficulty of findmg any evidence of 
the differential survival value of any of the characters in ques- 
tion.’’ ‘‘It is,’’ he says, ‘‘impossible to establish the fact of any 
advantage accruing to one of these species over its nearest allies 
by reason of its structural distinctions and difficult to find any 
satisfactory basis for a logical inference or conclusion to that 
effect.’’ 
Ritter carried the idea of coordinating the differences between 
two closely related species with the differences between their 
environments well toward a quantitative determination, with the 
result summarized in the following: ‘‘So far as the present 
inquiry has gone, the attempt to find a causal relation, or a 
necessary correlation, between the character differentials of the 
two species (Halocynthia johnsoni and H. haustor) and their 
environmental differentials, has produced negative results. In 
other words, the results do not enable us to affirm anything more 
definite about the adaptation of H. johnsoni to its environment 
