THE AMERICAN JOURNAL 
OF 
ANATOMY 
EDITORIAL BOARD 
CHARLES R. BARDEEN, GEORGE 8. HUNTINGTON, 
University of Wisconsin. Columbia University. 
HENRY H. DONALDSON, FRANKLIN P. MALL, 
The Wistar Institute. Johns Hopkins University. 
THOMAS DWIGHT, J. PLAYFAIR McMURRICH, 
Harvard University. University of Toronto. 
SIMON H. GAGE, CHARLES 8. MINOT, 
Cornell University. Harvard University. 
G. CARL HUBER, GEORGE A. PIERSOL, 
University of Michigan. University of Pennsylvania. 
HENRY McE. KNOWER, Secretary, 
University of Cincinnati. 
VOLUME xX 
PUBLISHED QUARTERLY BY 
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY 
36th STREET AND WOODLAND AVENUE 
PHILADELPHIA,-PA. 
