644 12. BOIDJ\1. COLUBRID& 



County, at Hope, Bonner County, and on Fish Haven 

 Creek, Bear Lake County. 



Habits. Like the Pacific Boa, this snake has the habit 

 of pretending that its very blunt tail is its head. This is 

 well shown in the photograph of a living specimen (Plate 

 60), where the end of the tail, held somewhat elevated and 

 protected by the coils of the snake, might easily be mistaken 

 for a head and perhaps save the real head from attack. 

 These snakes thus merit the popular name Two-headed 

 Snake. 



Family 13. COLUBRID^ 



This family contains a large number of snakes in which 

 the belly is covered with a series of large plates 5 the head 

 plates are large and more or less regular; the eye is always 

 well-developed, but its pupil may be either round or ellip- 

 tical} there are no rudiments of limbs or pelvis; both jaws 

 are toothed, without poison-fangs near the front of the 

 mouth. 



Snakes of western North America have been referred 

 to 19 genera belonging to this family. These may be 

 identified by the following 



SYNOPSIS OF GENERA 

 a. Scales smooth. 



b. Anal plate divided; urosteges in two series. 

 c. Loreal plate absent. 



d. Anterior nasal united with internasal, sometimes 

 meeting its mate on top of the snout; rostral 

 prominent, greatly depressed; scales in 13 rows. 



Chilomeniscus. p. 868. 

 d'. Internasal distinct, anterior nasal not extending 



onto tep of head; rostral not depressed, 

 e. Rostral not turned up at tip; scales in 15 rows. 



Tantilla. p. 875. 



