CHAPTER XLI : THE OPISTHOGLYPH SNAKES OF 

 NORTH AMERICA 



A Division of Mildly Poisonous Serpents, with Grooved Fangs in 

 the Rear of the Upper Jaw — The Many Species Occur in 

 Both the Eastern and the Western Hemispheres 



Classification and Distribution. — The Opisthoglyph snakes 

 form a division of the family Coluhridce. From the other mem- 

 bers they are readily separated by the presence of a pair, or several 

 pairs of grooved teeth in the rear oj the upper jaw. These snakes 

 are divided into three sub-families, seventy-nine genera and a 

 very large number of species. But one of the sub-families is 

 represented in the New World — the Dipsadomorphince, a few 

 species of which occur in the southern portions of the United 

 States. There are numerous species in Mexico, Central America 

 and tropical South America, but the greater number inhabit Asia. 



General Characters. — It is the popular idea that the poisonous 

 serpent may generally be told by its thick body and wide, tri- 

 angular head, and that a few venomous species of the New World 

 — the Coral Snakes (Elaps) — resemble the harmless serpents in 

 outlines but may be at once distinguished by their colouration. 

 These conclusions are incorrect. As to the inconsistency of brand- 

 ing a snake as poisonous because it has a broad and flat, triangular 

 head, the student is referred to the many species of thick-bodied, 

 harmless serpents described and illustrated in the preceding 

 pages. In regard to the idea of the Coral Snakes forming the few 

 exceptions where venomous snakes resemble the slender-bodied, 

 harmless species, the succeeding pages, dealing with the Opis- 

 thoglyph serpents, will be found to explain conditions quite to the 

 contrary. 



Aside from those snakes representing in North America 

 the sub-family Crotalince — the Pit Vipers, and the sub-family 

 Elapince — the Coral Snakes, there are various species of poisonous 

 serpents. This is a condition not generally understood as the 

 Opisthoglypha has either been classed as a group comprising 



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