C. Proteroglypha, with the anterior maxillary teeth grooved or canaliculated.
The third, which is not represented in Europe, includes some of the most deadly snakes, such as the Cobras, Kraits, Death-adders, etc.
The European genera are thus distributed in the two other series:
Aglypha (Colubrinæ): Tropidonotus, Zamenis, Coluber, Coronella, Contia.
Opisthoglypha (Dipsadomorphinæ): Cœlopeltis, Macroprotodon, Tarbophis.
These genera give but a feeble idea of the variety of forms included in this family, which comprises adaptations to every mode of life for which snakes are fitted.
The distribution of the family coincides with that of the order, extending over the whole world with the exception of the Arctic and Antarctic regions, and Ireland and New Zealand, as well as most of the smaller islands of the Pacific Ocean.
Maxillary teeth increasing in size posteriorly. Head more or less distinct from neck; eye moderate or rather small, with round pupil. Body more or less elongate; scales keeled, with apical pits. Tail moderate.
This large genus, comprising about ninety species, and of almost cosmopolitan distribution, with the exception of South America and the greater part of Australia, may be divided into several subgenera, two of which are represented in Europe—Tropidonotus proper, with the common T. natrix, and Nerodia, Baird and Girard, with two closely related species of more thoroughly aquatic habits, T. tessellatus and T. viperinus.