No. 562] VARIATIONS IN NUMBER OF VERTEBRJE 



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in 6 specimens, and while in different directions in the 

 remaining 10, in only 5 do the deviations in the two mem- 

 bers approach equality and in four of these the deviation 

 from the average is very small in both series. 



Variation in R. grahami. — From the above results one 

 may conclude that if the same correspondence in the 

 number of ventral scutes and vertebra? prevails in nearly 

 related forms the form with the most scales will have the 

 most vertebrae. To test this point in the genus studied a 

 small series of males (all that were available) of R. 

 grahami were examined. The results are shown in the 

 following table : 



It will be noted that the same close correspondence in 

 scutes and scales is indicated in R. grahami as has been 

 demonstrated for R. leberis, and that notwithstanding 

 the fewer vertebrae in the tail the former species has a 

 decidedly larger number of vertebrae and scutes. There 

 is no reason to believe that the females of R. grahami will 

 not show a similarly higher number of scales and the same 

 relation between scutes and vertebrae. 



Summary and Conclusion 

 The variation in series of R. leberis may be summar- 

 ized as follows : 



1. The number of belly scutes is practically the same 

 as the number of body vertebrae, and the number of sub- 

 caudal scutes is between two and three less than the 

 number of caudal vertebrae. 



2. The sexual differences consist of an average of less 



