Celebrating its one hundred and twenty-fifth birthday, the Academy of Natural Sciences of Philadelphia assembled a remarkable scientific congress in that city, from Wednesday, March 17, until late Saturday, March 20, 1937. Rarely, if ever, in the history of American natural science has there been such a happy combination of scientific discussion, presentation of new evidence, and the gathering of exhibits, all bearing on the worldwide problem of man's origin and early development. Even more appreciated was the unlimited hospitality of the Academy which transmuted what might have been merely a stimulating scientific symposium into a gracious international social event.