276 THE OSTEOLOGY OF THE REPTILES 



Family Typhlopidae. No ectopterygoids or tabulars. Maxillae 

 vertical, toothed; maxillae and mandibles edentulous. Vestiges of 

 pelvis present. 



The Typhlopidae with but a single living genus and about one 

 hundred species are widely distributed in the tropical regions. They 

 are burrowing in habit. A single extinct form {Symoleophis Sauvage) 

 from the Cretaceous of France (Senonian) has been referred here; the 

 single known vertebra is more probably that of a dohchosaur lizard. 



Family Boidae (Pythonidae). Ectopterygoid and coronoid pres- 

 ent. Maxillae horizontal, reaching premaxillae, with sohd teeth, the 

 latter with or without teeth. Tabular long, or short and closely 

 attached to the skull (Illysiidae) . Vestiges of hind hmbs present. 



A family of wide distribution comprising about sixty species, some 

 of them attaining a length of nearly thirty feet. Boas, anacondas, 

 pythons, etc. 



Upper Cretaceous. Dinilysia Woodward, Patagonia. 



Eocene. Protagaras Cope, Limnophis Marsh, Lestophis Marsh, 

 Boavus Marsh, North America. 



Oligocene. Paleopython Rochebrune, Scytalophis Rochebrune, 

 France. Paleryx Owen, England. 



Miocene. Heteropytlwn Rochebrune, Scatophis Rochebrune, 

 France. Aphelophis Cope, Ogmophis Cope, Calamagras Cope, 

 North America. Botrophis Mercer, France. 



Pliocene. Python Daudin, East India. 



Family Paleophidae. Neural spines elongate; vertebrae with an 

 inferior ridge. 



Large snakes, probably subaquatic, imperfectly known. 



Eocene. Pterosphenus Lucas, Paleophis Owen, North America. 

 Paleophis Owen, Europe. 



Family Viperidae. No coronoids. Ectopterygoids present. Max- 

 illae vertically erectile, articulating with prefrontal, excavated 

 (Crotalinae) or not (Viperinae). Poison fangs perforated. 



About one hundred living species of these poisonous snakes with 

 erectile fangs are known, widely distributed. Pit vipers (rattlesnakes 

 and copperheads) exclusively in America.^ 



' [Occur also in Asia and Malaysia. — Ed.] 



