27 



Big Bend National Park. AMERICAN MIDLAND NATURALIST 75(1): 

 61-100. 



Cnemidophorus tigris marmoratus is among the species discussed. 

 The topography and climate of the area is discussed in detail, along 

 with earlier herpetoiogical investigations. A method of estimating 

 lizard densities by counting active lizards is developed and compared 

 with some poor attempts by the investigator to do the same by live- 

 trapping. Sources of error are discussed. Six study plots were es- 

 tablished along an elevational transect and studied for 2 years. A 

 highly significant correlation of lizard numbers with elevation was 

 established. The corollary contributions of vegetation structure, 

 soil, rainfall and temperature to this correlation are discussed. No 

 distinct conclusions seem to actually be reached by the author. 



72. — . 1977. A changing environment: documentation of lizards and 

 plants over a decade, m TRANSACTIONS OF THE SYMPOSIUM ON THE 

 BIOLOGICAL RESOURCES OF THE CHIHUAHUAN DESERT REGION, 

 UNITED STATES AND MEXICO. R. H. Wauer and D. H. Riskind, editors. 

 U. S. Dept. Interior, National Park Service Transactions and Pro- 

 ceedings Series No. 3: 533-555. 



The same area is re-visited and the same methods used in 1968 and 

 1969 as was done in 1966 by this author. Lizard population density es- 

 timates are given for each study quadrat. It is suggested that an in- 

 crease in vegetation density up to a certain optimum for each lizard 

 species will result in an increase in population density for that spe- 

 cies; increases above that vegetation optimum will result in a decrease 

 in lizard population density. Cnemidophorus tigris is shown to prefer 

 relatively open areas and is suggested to outcompete at least one other 

 congener (septemvittatus) . 



73. Dessauer, H. C, W. Fox and F. H. Pough. 1962. Starch-gel elec- 

 trophoresis of transferrins, esterases and other plasma proteins of hy- 

 brids between two subspecies of Whiptail lizard (genus Cnemidophorus ). 

 COPEIA 1962(^): 767-77^. 



Twenty protein bands were identified in _C. tigris gracilis, _C. t. 

 marmoratus, and hybrids between the two; 12 bands were common to both 

 subspecies and ^ were unique to each. F^ and backcross hybrids were 

 found, indicating that hybrids are fertile. The zone of hybridization 

 in SE Arizona-SW New Mexico appears broader than indicated by Zweifel 

 (1962), although this paper supports that one in other respects; is in- 

 deed complementary to it. 



7*. Douglas, C. L. 1966. Amphibians and reptiles of Mesa Verde Na- 



