REVISION OF THE KING SNAKES. 185 



while on the rest of the head various portions of the elaborate pattern 

 of triangulum appear, commonly a dark-edged light spot over each 

 eye, and more or less of a light band from behind or over the eye to 

 the side of the neck, bordered below by a dark band from the eye to 

 the angle of the mouth. As the range of triangulum is approached 

 the head markings characteristic of that form attain greater perfec- 

 tion, and some specimens show a tendency to a dorso-lateral fusion 

 of the dark borders of the first whitish cross band, to inclose an oval 

 or Y-shaped spot of white or gray within the ground color of the head 

 on its posterior portion. This and the shortening and narrowing of 

 the dorsal saddles are the slowest of the characteristics of triangulum 

 to appear, and when they have been attained, we say that we have 

 triangulum. 



Thus, syspila is central both geographically and structurally to 

 the three forms, triangulum, amaura, and gentilis, and with each of 

 these forms intergradation takes place in the region of the common 

 boundary of the respective ranges. 



