The Opisthoglyph Snakes of North America 



The Genus Trimorphodon: This is essentially a Central 

 American and Mexican genus. But one species ranges north- 

 ward into the United States. All of the species are of moderate 

 size some reaching a length of a yard and the thickness of a 

 man's forefinger. The neck is slender, but the head is broad, 

 flat and very distinct, with large eyes, having a cat-like (elliptical) 

 pupil. The species look like viperine, poisonous snakes and their 

 temper is not of the best. The food consists of lizards, young 

 snakes and batrachians frogs and salamanders. 



THE JEW'S-HARP SNAKE 

 Trimorphodon lyrophanes, (Cope) 



Moderate in size two and a half to three feet in length. 

 Rather slender; neck very slender; head broad and very distinct 

 swollen at the temples, and with large eyes, the pupils elliptical. 



Colouration. Light gray; about twenty pairs of deep brown 

 blotches on the back (to the base of tail); tail also blotched. 

 There is an irregular row of blotches on the sides. Abdomen 

 white; dark spots on the edges of many of the shields. 



On the top of the head is a large patch of deep brown, its out- 

 lines suggesting those of a jew's-harp. 



Dimensions. Total Length 30 inches. 



Length of Tail 6 



Greatest Diameter f " 



Width of Head | " 



Length of Head i| 



Distribution. Southern Arizona; Lower California. 



The Genus Sibon: Formation and size similar to the pre- 

 ceding genus, but there is a single loreal plate in place of two as 

 existing with Trimorphodon. Seven species comprise this genus. 

 They inhabit Mexico and Central America. One extends north- 

 ward into southern Texas. 



THE ANNULATED SNAKE 

 Sibon septentrionalis, (Kennicott) 



Size moderate; body rather slender, the tail gradually 

 tapering to a slender tip. Head very broad and distinct from 

 neck; swollen at the temples. Eyes large, with elliptical pupil. 

 Ventral plate divided like the preceding species. 



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