CLASS REPTILIA 539 



ventral scales transversely enlarged; eyes functional 



and free. 

 Subfamily 1. Pythonin^e. Pythons. — Examples: Lox- 



ocemus, Liasis, Python (Fig. 460). 

 Subfamily 2. Boin^e. — Boas. — Examples: Epicrales, 



Boa, Ungalia. 

 Family 4. Colubrid^e. — Harmless and Poisonous 



Snakes. — Serpentes with facial bones movable; both 



jaws toothed. 

 Series A. Aglypha. — • Colubrid^e with solid teeth, not grooved 



or •tubular. Non-venomous. 

 Subfamily 1. Colubrin^e. — Typical Harmless 



Snakes. — Examples: Thamnophis (Fig. 461), Zame- 



nis, Elaphe. 

 Series B. Opisthoglypha. — Colubrid^e with grooved fangs in 



the rear of the upper jaw. Venomous. 

 Subfamily 2. Homalopsin^e. — River Snakes. — Ex- 

 amples: Hypsirhina, Homalopsis. 

 Subfamily 3. Dipsadomorphin^e. — Examples: Tantilla, 



Philodryas, Oxyrhopns. 

 Series C. Proteroglypha. — Colubrid^e with fangs in the 



front of the upper jaw. Venomous. 

 Subfamily 4. Hydrin^e. — Sea-snakes. — Examples': 



Hydrophis, Distlra, Platurus. 

 Subfamily 5. Elapin^e. — Cobras and Coral-snakes. — 



Examples: Naja (Fig. 462), Elaps, Denisonia. 

 Family 5. Viperid^e. — Thick-bodied Poisonous Snakes. 



— Poisonous Serpentes with a pair of large perforated 



fangs. 

 Subfamily 1. Viperin^e. — True Vipers. — Examples: 



Viper a, Atractaspis. 

 Subfamily 2. Crotalin^e. — Pit-vipers. — Examples: 



Crotalus (Fig. 466X Agkistrodon (Figs. 463 and 464). 



Lachesis. 



