Colubridae (colubrid snakes; order Squamata, suborder Serpentes) The largest family of snakes, most of which are harmless and have solid teeth, but some of which are venomous, with teeth at the back of the jaws grooved for venom. The left lung is small, or absent. They have no trace of hind limbs. Members of the genus Natrix are usually found near water, where they feed on amphibians and small mammals. N. maura (viperine snake), of the Mediterranean region, grows to almost 1 m and bears markings similar to those of the adder, from which it can be distinguished by the round pupils of its eyes (those of an adder are vertical). N. natrix (grass snake or ringed snake) is widely distributed in Europe. N. tessellata (dice snake or tessellated snake) whose range extends from central Europe to central Asia rarely exceeds 1 m in length. Coluber viridiflavus (dark-green whip snake, European whip snake, or western whip snake), found mainly in France, southern Switzerland, and Italy, grows to a maximum of about 1.9 m and is harmless to humans, but aggressive and agile. Coronella austriaca (smooth snake) of Europe and western Asia rarely exceeds 70 cm in length; it is ovoviviparous. Elaphe longissima (Aesculapian snake) of central and southern Europe grows to 2 m, E. quatuorlineata four-lined snake), whose range extends into the southern USSR and Iran, grows to 2.5 m, and E. situla (leopard snake), of southern Europe and the Near East, grows to 1 m. Dispholidus typus (boomslang) is the only member of the family whose bite may be fatal to humans; it is an agile tree snake (its common name means ‘tree snake’ in Afrikaans), up to 1.8 m long, found in the African savannah. There are about 1000 colubrid species, distributed throughout the world. See also EGG-EATING SNAKES.