58 



Christopher W. Brown and Carl H. Ernst 



7" 



Fig. 1. Range of Crotalus horridus (from Klauber 1972). 



County and southward as intergrades, because the specimens of atri- 

 caudatus from counties bordering the Mississippi River more closely 

 resembled horridus in some characters. 



A study by Pisani et al. (1973) concluded that, on the basis of 13 

 morphological characters, the recognition of subspecies in C. horridus 

 could not be justified. They examined specimens from localities through- 

 out the range, including western populations where intergradation is 

 thought to occur. 



The purpose of this study was to examine variation in pattern and 

 adult size differences in addition to those morphological characters used 

 by Pisani et al. (1973) in eastern C. horridus to determine if a more 

 comprehensive study of the species is needed. 



MATERIALS AND METHODS 



Data were obtained on 337 museum specimens from New Hamp- 

 shire, Vermont, Massachusetts, Connecticut, New York, New Jersey, 

 Pennsylvania, Maryland, Virginia, North Carolina, South Carolina, 

 Georgia, and Florida. However, only 101 specimens were suitable for 

 the analyses used here in that they were complete in all characters exam- 

 ined. Twenty-one specimens were from localities of probable intergrada- 

 tion, and so were treated separately. Of the remaining 80, 10 were juve- 

 niles and were eliminated from some analyses. Localities of the 101 

 specimens used are shown in Figure 2. The characters used in this study 



