Maxillary, palatine, and pterygoid bones movable; transverse bone present; pterygoid extending to quadrate or mandible; supratemporal present, attached scale-like to cranium, suspending quadrate; prefrontal not in contact with nasal; maxillary horizontal, not movable perpendicularly to the transverse bone; no coronoid bone. Teeth in both jaws. No vestiges of pelvic arch. An enormous group, comprising the great majority of snakes. Divided into three parallel series: _A._ Aglypha, with all the teeth solid. _B._ Opisthoglypha, with one or more of the posterior maxillary teeth grooved. _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): _Coelopeltis_, _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. GENUS TROPIDONOTUS, KUHL 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_. 3. TROPIDONOTUS NATRIX, Linnæus (_Natrix vulgaris_, Laurenti; _Coluber torquatus_, Lacepède) The Grass-Snake, or Ring-Snake _Form._--Moderately slender; snout short, obtuse, not prominent; eyes and nostrils lateral, the former moderately large. Tail four to six and a half times in the total length.