1893.] The Color Variations of the Milk Snake. 1071 
The relations of these forms may be expressed in a tabular 
form as follows: 
gentilis 
polysonus | 
annulatus 
conjunctus 
| 
coccineus 
| 
syspilus 
temporalis 
parallelus 
doliatus 
collaris 
clericus 
triangulus 
The main series corresponds with a distribution in latitude, 
commencing with the triangulus of New England and New 
York, and passing gradually to the coccineus of the Gulf coast 
regions, and polyzonus of Mexico and Central America. The 
forms of the right hand column are (except the parallelus), 
from the central warmer parts of the continent. I think this 
series of color forms of the Ophibulus doliatus demonstrates 
three points. First; the series is determinate and not indeter- 
minate. Second; the patterns have relation to latitude; the 
tendency being to make the spot color of the upper regions 
red, and to extend the area of this color more and more, 
as we proceed southwards. Third; so far as regards eastern 
North America, there is a diminution of size in passing from 
north to south; the O. d. coccineus being the smallest of the 
subspecies. In Mexico, the size is recovered, as the O. d. 
polyzonus equals in dimensions the O. d. triangulus. 
