VARI.VnON IN THE COMMON GARTErt-SNAKE. 177 



Males with tail twenty- four per cent, total length or over, averaged 75 

 urosteges. 



Males with tail less than twenty-three per cent, length, averaged 71 

 urosteges. 



Females with tail twenty-one per cent, total length or over, averaged G5 

 urosteges. 



Females with tail less than twenty per cent, length, averaged fil 

 urosteges. 



GREATER VARIABILITY OF THE FEMALE. 



One of the points in which there seemed to be considerable individual 

 variation was the number of right and left upper and lower labials, and 

 the tabulation showed that seven per cent, more of the females were 

 variable in this respect than the males. 



Seventy-eight per cent, of the females had labials ,^3^^ (regular). 



7—7 



Eighty-five per cent, of the males had labials j^— , (regular). 



One other interesting fact came to light, though it may not have any 

 significance and probably would change if a larger number were 

 examined. 



Nineteen abnormal females showed thirty-three variations of which 

 fifty-five per cent, were added plates. 



Nine abnormal males showed eleven variations of which none were 

 added plates. 



Statistics also showed that the lower jaw was more variable than the 

 upper. Of the 148 individuals examined, eighty-eight per cent, of the 

 females and ninety-eight per cent, of the males, averaging ninety-four 

 per cent, of the total number, had the normal number of labials in the 

 upper jaw (7-7), while only eighty-six per cent, of the females and 

 eighty-seven per cent, of the males, eighty-six per cent of the total num- 

 ber, had the normal number (10-10), in the lower jaw. There was no 

 marked difference between the right and left sides. Twenty-five of the 

 forty-four aberrations were on the left side and nineteen on the right. 

 Of the fifteen aberrations in the upper labials, six were on the right side 

 and eleven were added plates. Of twenty-nine aberrations in the lower 

 labials, thirteen were on the right side and seven were added plates. 



SIMILARITY BETWEEN VARIATIONS IN GARTER-SNAKES AND WATER-SNAKES. 



When a comparison was made between the results of my season's 

 work and that of Dr. Clark upon the forms of ISfatrix, it was interesting 

 to find that there was a striking similarity between the variations in 

 these two genera. The difterences, due both to age and sex, are in many 

 cases almost identical. The water-snakes show the same greater rela- 

 tive length of head and tail in the young that is found in the garter- 

 snake. The range in the number of urosteges in the two species of water- 

 snake was 58-82, while in the garter-snake it was 57-81. The same cor- 

 relation between length of tail and number of urosteges was observed 

 in both genera. In the water-snakes, as in the garter-snakes, the fe- 

 males showed greater variability in the number of labials and the simi- 

 larity was carried through to the end by finding that the greater varia- 

 bility of the lower jaw, and lack of distinction between the left and right 

 sides held in both forms. The only ditfereuce observed was in the rela 

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