PREFACE. 
BY-LAW of the National Academy of Sciences 
(XVIII.) makes it the duty of the Secretaries to 
prepare an Annual, and to publish the same on the first | 
day of each year. As but one meeting, that for organiza- 
tion, was held in 1863, the Secretaries were excused from 
the duty during that year, and the Annual now presented 
is intended to cover the whole period from the organization 
of the Academy in April, 1863, to January 1st, 1865. 
WOLCOTT GIBBS. 
LOUIS AGASSIZ. 
