Life histories. 



Among the subjects imperfectly known are rate of growth under normal 

 and favorable conditions, time taken to reach sexual maturity, frequency of 

 shedding of skin, amount of wandering or adherence to a definite range, and 

 records of longevity. It is possible to mark snakes for future identification by 

 snipping into one or more of the ventral plates. A scar or scars result which 

 persist throughout life. 



Food habits. 



These are difficult to study without sacrificing many animals. UnfortU' 

 nately the digestion of snakes is so efficient that the feces usually contain httle 

 identifiable material. However, one may sometimes observe the attempts of 

 free snakes to swallow unusual or unexpected prey. Also, one can investigate 

 the stomach contents of reptiles killed by automobiles or unsympathetic people. 

 A surprising number of snakes can sometimes be picked up on state highways. 

 The author secured only slightly damaged specimens of twelve different species 

 on paved roads during a summer's automobile trip from Massachusetts to Iowa. 

 In the southern states the number of snakes available in this way is even greater. 



OUTLINE OF CLASSIFICATION OF NATIVE SNAKES 



Order SQUAMATA (of Class REPTILIA) 



With one temporal opening on each side, between parietal and the 

 squamosal'postorbital bar; with one occipital condyle; no uncinate pro' 

 cesses on ribs; no epipubic bones 

 Suborder SERPENTES Snakes 



Brain case completely ossified; all skull bones except those of the brain 

 case articulated; usually without traces of Hmbs or girdles 

 Family LEPTOTYPHLOPIDAE Blind Snakes 



Small, blind, worm-like, burrowing snakes; belly of native 

 species with small scales instead of ventral plates 

 One genus — Leptotyphlops (2 species) 

 Family BOIDAE Boas 



Smooth-scaled; native species with vertical pupils and short, ob- 

 tuse tails, with undivided subcaudal plates 

 Two genera — Uchanura (1 species) 

 Charina (1 species) 

 Family COLUBRIDAE Colubrine Snakes 



An extremely large and varied group, with over one hundred 

 native species; pupil round; scales smooth or keeled; no elon- 

 gate poison fangs among the front teeth, but in a few forms 

 some of the back teeth are long and grooved to form poison 



388 



