Page:Encyclopædia Britannica, Ninth Edition, v. 22.djvu/210

 SNAKES Indian rat snakes. animals, such as worms, larvae, and burrowing insects. They are found in all tropical countries and the parts ad- joining, and some of the small species have a wide range, having been probably transported by accident on floating objects to distant countries. Some species attain to a length of 24 inches, whilst others scarcely grow to one- fourth that size. An almost unbroken series leads from these degraded worm-like snakes to the typical ColubridsR, of which the Smooth Snake of Europe (Coronella), the Corn Snake of North America (Coluber), the Rat Snake of India and South America (Ptyas, Spilotes), ^Esculapius's Snake of the south of Europe, the common Ring Snake of England (Tropidonotus), are well-known representatives. Smooth The Smooth Snake (Coronella leevis) is common in the snake, warmer parts of Europe, extending northwards into the New Forest district of England. In coloration, general habits, and size it somewhat resembles the viper ; but, although it is rather fierce and ready to bite when caught, it is quite harmless and soon becomes tame in captivity. The shields on its head readily distinguish it from the viper. Its chief food consists of lizards, and it attains a length of 2 feet. The Indian Rat Snakes (Ptyas mucosus and P. korros) are two of the most common species of India, the former in- habiting India proper and Ceylon, the latter the East Indian Archi- pelago, Siam, and southern China. P. mucosus is a powerful snake, attaining to a length of 7 feet, the tail being one -third or rather more ; it is easily recognized by having three loreal shields, one above the other two ; its scales are arranged in seven- teen rows. Its food consists of mammals, birds, and frogs ; and it frequently enters the dwellings of man, rendering itself useful by clearing them of rats and mice. It is of fierce habits, always ready to bite; when irritated it utters a peculiar diminuendo sound, not unlike that produced by a tuning-fork when struck gently. ^Esculapius's Snake (Coluber sssculapii) was probably the species held in veneration by the ancient Romans. It grows to a length of about 5 feet, is of mild disposi- tion, and can be readily domesticated. Its original home is Italy, where it is common, but it has extended its range northwards across the Alps into the south of France, and thence into northern Spain. Following the course of the Inn and the Danube, it has reached the Black Sea ; and it is also now common in several local- ities along the middle parts of the Rhine. From direct observations made JilllS 8 snake. range. Naturalists believed formerly that the occurrence of this snake at widely distant and isolated localities was due to its introduction by the Romans, who had settle- ments in those localities. The common British Snake or Ring Snake (Tropi- British donotus natrix) is extremely common all over Europe ril 'S (except in the northern parts), and belongs to a genus sn extremely rich in species, which are spread over Europe, Asia, India, Australia, and North America. Some of the species, like the Indian T. quincunciatus and T. stolatus and the North- American T. ordinatus, are perhaps more abun- dant as regards the number of individuals than any other snake. T. natrix is easily recognized even at a distance by two yellow or white spots which it has behind its head. It grows rarely to a length of 4 feet ; it never bites, and feeds chiefly on frogs and toads. Its eggs, which are of the size and shape of a dove's egg, and from fifteen to thirty in number, are deposited in mould or under damp leaves, and are glued together into one mass. A very peculiar genus of snakes, Dasypeltis, represented Egg- by three species only, is the type of a separate family and eaters - is restricted in its distribution to Central and South Africa. In Cape Colony these snakes are well known under the name of " eyervreter," i.e., " egg-eaters." Their principal diet seems to consist of eggs, their mouth and oesophagus FIG. 8. Head of Herpeton tentacidatus. during the last twenty years there can be no doubt that it is still extending its FIG. 9. Dasypeltis unicolor, in the act of swallowing a fowl's egg. being so distensible that an individual scarcely 20 inches in length, and with a body not surpassing a man's little finger in circumference, is able to swallow a hen's egg. The teeth in the jaws are very small and few in number ; but the inferior processes of the posterior cervical vertebrse are prolonged, and provided with a cap of enamel, and penetrate the oesophagus, forming a kind of saw. As the egg passes through the oesophagus its shell is broken by this apparatus, and, whilst its contents are thus retained and swallowed without loss, the hard fragments of the shell are rejected. This peculiar apparatus occurs also in another snake, Elachistodon, which belongs to the Indian fauna and has been referred (provisionally) to the family Amblycephalidee. Also two prominences at the base of the skull of the Indian Coronelline Nympliopliidium probably have the same function. Besides the snakes mentioned, we have observed species of Dipsas feeding on eggs of parrots, the eggs reaching the stomach entire, as these