Variation in Crotalus horridus 



69 



Table 4. Mean character values (x) and standard deviations (s) of all 19 charac- 

 ters for the two subspecies of Crotalus horridus. Numbers in paren- 

 theses are sample size. One specimen from each subspecies was not 

 included because of unknown sex. M = male, F = female. 







C. h. 



horridus 







C. h. atricaudatm 







M 



(14) 



F(21) 



M(ll) 



F 



(22) 





x, 



s 



x, 



s 



x, 



s 



x, 



s 



ADS 



25.29, 



1.54 



25.38, 



0.97 



27.54, 



1.44 



26.14, 



1.64 



DSM 



23.43, 



1.22 



23.38, 



0.80 



24.46, 



0.93 



24.18, 



1.05 



PDS 



18.57, 



0.76 



18.67, 



0.73 



19.27, 



0.65 



19.00, 



0.62 



VS 



163.00, 



2.94 



166.67, 



3.42 



167.09, 



2.34 



169.54, 



3.04 



CS 



23.64, 



1.01 



19.81, 



1.12 



25.54, 



2.66 



20.23, 



1.90 



DCS 



1.50, 



1.65 



1.48, 



1.03 



3.18, 



2.99 



1.04, 



1.13 



LSL 



13.86, 



0.86 



13.71, 



1.10 



13.36, 



0.92 



14.09, 



0.92 



RSL 



13.86, 



1.01 



13.33, 



0.86 



13.27, 



0.90 



14.00, 



0.98 



LIL 



14.50, 



1.02 



14.76, 



0.89 



15.54, 



0.69 



15.04, 



0.95 



RIL 



15.21, 



0.70 



14.86, 



1.01 



15.54, 



1.29 



15.18, 



1.14 



BCB 



11.14, 



3.50 



9.14, 



3.90 



12.54, 



3.67 



11.82, 



2.58 



TCB 



0.57, 



1.02 



0.00, 



0.00 



1.54, 



2.12 



0.36, 



0.95 



R 



0.09, 



0.01 



0.07, 



0.00 



0.09, 



0.01 



0.07, 



0.01 



SVL 



939.71, 



133.96 



849.52, 



59.77 



1049.91, 



128.87 



1097.91, 



116.14 



TL 



81.71, 



10.62 



56.95, 



5.52 



91.00, 



13.03 



72.86, 



8.17 



HL 



42.42, 



4.36 



39.25, 



2.98 



47.52, 



4.57 



48.24, 



4.34 



MS 



0.29, 



0.47 



0.10, 



0.30 



1.00, 



0.00 



0.86, 



0.35 



GC 



0.36, 



0.50 



0.67, 



0.48 



0.09, 



0.30 



0.41, 



0.50 



POS 



0.29, 



0.47 



0.14, 



0.36 



0.82, 



0.40 



0.96, 



0.21 



them into the C. h. horridus group. Of the properly classified C. h. 

 horridus specimens, about 20% possessed an indistinct stripe and 90% 

 lacked one altogether. 



Since adult size and middorsal stripe appear to be the most impor- 

 tant factors, one plotted against the other (factor 1 versus factor 4) 

 should yield good separation of the groups along both axes, which is the 

 case in Figure 5F. Crotalus h. atricaudatus clusters in the first quadrant, 

 and C. h. horridus in the third quadrant. The individuals lying outside 

 their respective clusters are a combination of aberrant individuals in the 

 previous plots and have already been discussed. 



Characters DSM, PDS, VS, BCB, and TCB were determined to be 

 the combination of variables that best discriminated in the discriminant 

 analysis of the first 13 characters. Pisani et al. (1973) reported characters 

 CS, VS, DSM, and R (in decreasing order of discriminating ability) as 

 the most discriminating in their analysis. Some differences would be 

 expected in light of the different geographical areas sampled. In addi- 

 tion, the method of counting crossbands was different in this study (see 



