54 
ORGANIC DEPENDENCE AND DISEASE 
of this Coblentzian species but have seen no other shell 
used for attachment nor have I found record of any other. 
Though it is not practicable to use percentages with 
reference to the frequency of this occurrence, the palpable 
fact remains that, as between these two closety allied if 
not identical corals, growing in different and remote basins 
of the sea, one selects a gastropod, the other selects a 
bracliiopod as its base of attachment. Emphasis is put 
on the word “ selects,’ ’ for among the brilliant examples 
of selective adaptation none could be more striking than 
this. The floor of the New York Devonian sea was covered 
with Chonetes and of the Rhenish sea with gastropods, dur- 
ing the life of this coral. Were either wanting in the 
other fauna, hundreds of other species of organisms lined 
the sea bottom. It is very impressive to find the evidence 
of this singular Devonian association of coral and worm 
from parts of the world as remote from each other as 
New York, northern Brazil, western Europe and Con- 
stantinople. The fact that in chronology the New York 
occurrence is later than the rest (Lower Devonian) seems 
to indicate a quick spread of this adjustment over the sandy 
sea bottom of the early Devonian of the world , 1 from which 
the deeper contemporary waters of New York were ex- 
cepted and in which region this symbiosis did not arrive 
till the next succeeding stage. Of its ultimate fate a nega- 
tive evidence permits us only to say that it went out with 
the Hamilton stage and did not return with the partial re- 
turn of that fauna in central New York during the time 
that is reckoned as of the next succeeding stage — the 
Ithaca-Portage time of the Upper Devonian. 
I have not attempted to escape the obvious interpreta- 
tion of these phenomena nor to avoid its expression in 
terms of psychic function. To biologists who still find the 
term “instinct” a comfortable receptacle for such reac- 
i Save in the early Devonian of austral latitudes where the fauna is very 
unlike that of the rest of the world. 
