250 UNIVERSITY OF COLORADO STUDIES 



Introduction to the Study of the Ants of Northern Colorado 215 



Introduction to the Study of Rocky Mountain Bees 179 



Irrigation Ditches 237 



Libby, Melanchthon F 201 



Northern Colorado Plant Communities 223 



Notes on the Flow of Water in Irrigation Ditches 237 



Phillips, John Burton . . 5, 159 



Plant Communities [of Boulder Park] 223 



Pre-Thalesian Philosophy 201 



Ramaley, Francis 9i, 22 3 



Robbins, W. W 112,115,179,215 



Rocky Mountain Bees 179 



Sex Differences and Variability in Color Perception 207 



Scientific Expedition to Northwestern Colorado in 1909 . . . *■» . . . 101 

 Study of Rocky Mountain Bees 179 



Tolland, Colo. [Mountain Laboratory at] 91 



University of Colorado Mountain Laboratory 91 



Williams, Clement C 237 



. 76® 



