348 
Psyche 
[December 
Acknowledgements 
We acknowledge the help of our assistants, undergraduate research 
participants and volunteers in censusing: David Ballestas, David 
Borg, William Davis, Sharon Ginsburg, Anne Hill, Dennis Johns, 
James Karpus, Gordon and Muriel Kerr, Ellen Levy, Jaclin Lewbin, 
David Messenger, David Mucha, Gerald Mussgnug, Marianne Nied- 
zlek, Ronald Outen, Frances Pivorunas, Joyce Redemsky (Mrs. 
Gregg Young), Wayne Schennum, Melvin Shemluck, Frank Slansky, 
Darelyn Weber (Mrs. Charles Handley), and David Werner. We 
thank Dr. Wallace Hansen, U.S. Geological Survey, Denver, for 
critically reading the manuscript; and Dr. Paul Ehrlich, Stanford 
University, for giving us a copy of the manuscript of Ehrlich et al. 
(1972). William Knott, Forestry Research Technician, Black Mesa 
Experimental Forest, has been most informative in the history, 
floristics, and climatology of Black Mesa. Dr. Raymond Price, 
former Director of the Rock Mountain Range Experiment Stations, 
allowed us to study populations in the experimental pastures and sent 
us reprints of their studies of the Black Mesa. We are grateful for 
the hospitality of George Klaitch, Manager of the X Lazy F Ranch, 
and the Colorado Synod of the Presbyterian Church for allowing us 
living and laboratory space at the ranch. The Forest Service land-use 
maps (T50N-R5-5-1/2W, T49N-R5-5-1/2W, and T49N-R6W), 
showing recent and projected timber sales, were supplied by R. M. 
Case, District Ranger. David Mucha’s photographic assistance on 
Plates 2 and 3 is gratefully received. Mrs. Mary Grant retyped 
several revisions of this paper. 
This study was partially supported by Grant GB-2201 from the 
National Science Foundation, four grants from the University of 
Illinois Graduate Research Board, two grants from the Society of 
the Sigma Xi (1963 and 1968), National Science Foundation Pre- 
doctoral Fellowships to Wayne Schennum, and to James Karpus, and 
National Science Foundation Undergraduate Research Participation 
fellowships to William Davis, Sharon Ginsburg, William Hill, Ger- 
ald Mussgnug, Marianne Niedzlek, Ronald Outen, Melvin Shem- 
luck and Joseph Wroblewski. 
Explanation of plates 2 & 3 
Plates 2 and 3 are quadrated by the Universal Transverse Mercator Grid 
(Zone 13) and in PI. 3 every linear 2.5 km is numbered on the ordinate 
and the abscissa. The combined number (ordinate and abscissa respectively) 
produces the code number of each quadrat and its demes (Figs. 1 and 2). 
The lower case letters distinguish demes within a single quadrat. If a deme 
occurs on a grid line, the locality is numbered according to the code number 
