CONTENTS 
Page 
Mathematics. — Spaces with Corresponding Paths . By L. P. Eisenhart 233 
Mathematics. — Number of Substitutions Omitting at Least one Letter in 
A Transitive Group By G. A. Miller 238 
Zooi^OGY. — Photic Orientation in Insects By S. 0. Mast 240 
Pai.eontoi.ogy. — Hesperopithecus, the First Anthropoid Primate Found in 
America By H. F. Osborne 245 
Pai.eontoi.ogy. — Recent Discoveries on the Antiquity of Man .... 
By H. F. Osborne and C. A. Reeds 246 
Statistics. — On the Measurement of a Physiqai. Quantity Whose Magni- 
tude is Influenced by Primary Causes beyond the Controi. of the 
Observer and on the Method of Determining the Relation between 
Two Such Quantities . . . . . . By W. A. Shewhart 248 
Physics. — Electronic Bombardment of Nickel • By H. E. Farnsworth 251 
Physics. — The Crystal Structure of Potassium . By L. W. McKeehan 254 
Physics. — Preliminary Report on the Ionization of Potassium Vapor by 
Light By R. C. Williamson 255 
Physics. — The Absorption of Light by Sodium and Potassium Vapors . 
By G. R. Harrison 260 
