CONTENTS 



Page 



Introduction 1 



Methods and definitions 2 



Zoogeographical discussion 6 



Acknowledgments 11 



Key to the Mexican genera 12 



Familj' Typhlopidae 18 



Genus Typhlops 18 



Family Leptotyphlopidae 20 



Genus Leptotyphlops 20 



Family Boidae 24 



Genus Constrictor 24 



Genus Lichanura 25 



Genus Ungaliophis 26 



Family Pythonidae 27 



Genus Loxocemus 27 



Family Colubridae 28 



Subfamily Sibynophiinae 28 



Genus Scaphiodontophis 28 



Subfamily Colubrinae 29 



Genus Adelphicoi 29 



Genus Amastridium 31 



Genus Arizona 32 



Genus Chersodromus 33 



Geuus Chilomeniscus , 33 



Genus Chionactis 35 



Genus Clelia 35 



Genus Coluber 37 



Genus Coniophanes 38 



Genus Conophis 42 



Genus Conopsis 44 



Genus Dendrophidion 46 



Genus Diadophis 46 



Genus Dipsas 49 



Genus DvT/adophis 51 



Genus Drymarchon 53 



Genus Drymobius 56 



Genus Elaphe 58 



Genus Enulius 61 



Genus Exelencophis 62 



Genus Ficimia 62 



Genus Geagras 64 



Genus Geatractus 64 



Genus Geophis 64 



Genus Gyalopion 70 



Genus Heterodon 71 



Genus Hypsiglena.. 72 



UI 



