No. 433-] SNAKES OF SOUTHERN MICHIGAN. 



to account. Possibly the young are born later than those of 

 sipedon, and careful searching in the late summer or early fall 

 may yet reveal some of them. 



2. Proportions. — When we come to compare the proportions 

 of sipedon and erythrogaster, we have to bear in mind the fact 

 that small snakes differ appreciably from large ones in the 

 relative lengths of head and tail, and diameter of the eye. Thus, 

 if we averaged all of the available sipedons and placed the 

 averages beside those of the available erythrogasters, we should 

 be led to some erroneous conclusions. For example, it would 

 then seem that sipedon has a distinctly longer head than ery- 

 throgaster. That this is not so may be made easily apparent 

 by taking the eight largest females and sixteen largest males 

 of sipedon and comparing with the eight females and sixteen 

 whole males of erythrogaster. This is as fair a choice as pos- 

 sible, since erythrogaster averages so much the larger, and 

 the proportions of males and females are so different. The 

 following table shows clearly the result of such comparison. 



Table V. 



