VARIATIONS OF GARTER-SNAKES. 15 



rarely captured. As Abbott (1890, 296-297) says of these and some 

 other snakes, "It is not a httle curious that considering the large 

 numbers of eggs that are found in the earlier part of summer so few- 

 small snakes are to be seen. I have never come across one less than 

 4 inches in length, except in the cases of the hog-nose snakes, men- 

 tioned above, and of those which I have ushered into day by uncere- 

 moniously breaking the egg before the occupants were quite ready to 

 emerge. Even larger snakes, those measuring 6 to 10 inches in 

 length, are by no means common." Abbott is inchned to attribute 

 this rarity of young snakes to enemies, but I believe it to be due, in 

 large part at least, in the garter-snakes, to the retiring habits exhib- 

 ited by the young snakes during this period of their life. In the 

 case of those observed in captivity this secretiveness lasted until the 

 first winter, and it is probably not until the following spring, at least, 

 that they begin to seek their food in the open. In disposition the 

 garter-snakes vary from the retiring, agile ribbon snakes to the more 

 stocky aggressive species, such as sirtalis and radix. As a group, 

 however, the adults are not retiring, a feature that combined with 

 their abundance makes them the most common and widely known 

 group of snakes in America. 



VARIATION. 



I have asserted that the first step in the search for relationships 

 is to determine the variability of the characters. The traits that 

 have been used in systematic work on the garter-snakes are the 

 number of rows of dorsal scales, labial, ventral, and subcaudal scutes, 

 the position of the stripes, comparative length of the chin shields, and 

 proportionate length of the tail. It is now my purpose to subject each 

 of these traits to an examination to determine whether or not they 

 are variable, and, if so, the nature and extent of the modifications or 

 variations. 



In investigating the variations it is essential that a distinction be 

 made at the beginning between individual, sexual, and geographic 

 variation, for it is evident that until such a distinction is made w^e 

 can not hope to determine the value of the traits in pointing out 

 affinities. In systematic mammalogy and ornithology these dis- 

 tinctions are made, but unfortunately in snakes they have been 

 largely ignored. For example, radix is generally described as possess- 

 ing usually 7, but occasionally 8, supralabial scutes. Now it is con- 

 ceivable that if no distinctions are made that the males might be 

 characterized by 7 and the females by 8, or the opposite, that the 

 variation is purely an individual one, or that there is an increase or 

 decrease in the number in certain parts of the range, and until the 

 actual conditions are ascertained there is little hope of determining 

 affinities, for if in this particular form the variation is individual the 



