1877.] The Flora and Fauna of the Florida Keys. 137 
remaining, through this tendency, less injuriously affected by 
adverse circumstances and consequently might still endure. 
(7.) In short, natural selection in the one case might find its 
fulcrum in the easy adjustment of characters; and in the other 
case in the inherited persistency in equilibrium, by which the 
organism would be rendered more or less indifferent to the 
injurious elements of the environment as well as to its favorable 
. phases. 
(8.) The intermediate individuals, by the hypothesis, would be 
those least fitted to persist in any case, and therefore would be 
few in number and rapidly eliminated. Then we should have a 
parallel series of species in two or even more genera, existing 
simultaneously. 
-) The above hypothesis would account for the special class 
coming under the paradox quoted, and has an important bearing 
on the interpretation of certain embryological changes. For other 
forms of Saltatory Evolution attention should be directed to the 
inherited tendency to equilibrium which is the converse of the in- 
herited tendency to vary, but which has hardly been granted the 
place in the history of evolution to which its importance entitles 
it. Mr. Darwin, whom nothing escapes, has apparently recog- 
nized it in his testimony to the “ remarkably inflexible organiza- 
tion ” of the goose. Other writers seem to have been chiefly at- 
tracted by the converse of this tendency, as, under the circum- 
stances, is most natural. 
It seems as if the preceding reasoning might serve as a key to 
many puzzling facts in nature, and perhaps deprive the catastro- 
Phists of their most serviceable weapon. 
HINTS ON THE ORIGIN OF THE FLORA AND FAUNA 
OF THE FLORIDA KEYS. 
BY L. F. DE POURTALES. 
URING several seasons passed on or near the Florida reefs 
and keys, engaged in sounding and dredging in the Gulf 
Stream, in the service of the United States Coast Survey, I had — 
Occasion to make a few observations on the vegetable and ani- 
mal inhabitants of the islands. They were of course made with- 
out system, only in such places where the steamer happened to 
be in stormy weather, and I have been obliged to complete them 
as much as possible by the observations of others. Incomplete 
, -as they still are, they are given in the hope of drawing the atten- 
