THE SNAKES 259 



longest of all Colubrine snakes, is the Black Rat 

 Snake, S. variabilis, a native of tropical America. 

 Twelve feet is the maximum length. However, a 

 twelve-foot specimen looks hardly bigger, Avhen coiled, 

 than a six-foot cribo, as the form is decidedly slender. 

 The scales are proportionately large. As there is a pro- 

 nounced ridge on the back, we again note the same, 

 permanently emaciated look as existing with the Indian 

 rat snake. Incidentally, it is appropriate to mention 

 that the species of Spilotes are in several localities called 

 Rat Snakes. S. variabilis is black, with white or yellow 

 blotches; on the abdomen the markings assume a tessel- 

 lated pattern. This is a bad-tempered snake. 



Grouped among the genera of large Colubrine snakes 

 feeding principally upon warm-blooded prey is Coluber, 

 The members are quite nearly related to Zamenis and 

 Spilotes. Excluding the strictly technical dilFerences, 

 it might be explained they are powerful constrictors, 

 feeding entirely upon mammals and birds; they have 

 a peculiarly flattened abdomen, forming a sharp, angu- 

 lar border with the sides of the body; the half a hundred 

 species inhabit both eastern and western portions of 

 the Northern Hemisphere from the temperate latitudes 

 to the tropics. The average species of Coluber is a 

 powerfully-built snake, about five feet long, with a 

 squarish head distinct from the neck, quite large ej^es 

 and feebly-keeled scales. The flattened abdomen and 

 glossy scalation are good characters for gross identifi- 

 cation. For the most part, the Colubers are prettily 

 colored, agile climbers and may lead a partly arboreal 

 life. In the stubborn slaughter of such snakes, the agri- 

 culturist little realizes the economic value of the reptiles 

 in destroying injurious mammals. The appearance of 

 numerous snakes in fields of grain and about the barns 



