426 REPTTLIA-ORDER ULSQUAMATA. 



with transversely elongated shields, while the upper surface is invested with 

 smooth overlapping scales. One of the most common kinds, which grows to 

 a length of about three feet, is met with from the Bay of Bengal to Oceania. 

 These snakes can crawl with ease on land, and specimens have been from 

 time to time met with at considerable distances inland. In addition to certain 

 features connected with the nostrils, the more typical members of the sub- 

 family which are arranged under several separate genera differ from the 

 preceding in having the under surface scaled like the back, although in some 

 forms more or less distinct vestiges exist of the enlarged shields. These 

 genera are to a great extent distinguished from one another by the characters 

 of the teeth, the most important among them being Hydrus, Hydrophis, and 

 Distira. Emerson Tennent writes that> "sea-snakes are found on all the 

 coasts of Ceylon. I have sailed through large shoals of them in the Gulf of 

 Manaar, close to the pearl-banks of Aripo. The fishermen of Calpentyn, on 

 the west, live in perpetual fear of them, and believe their bite to be fatal. 

 In the course of an attempt which was made to place a lighthouse on the 

 great rocks of the south-east coast, known by seamen as the Basses or Baxos, 

 the workmen who first landed found the portion of the surface liable to be 

 covered by the tides honeycombed and hollowed into deep holes filled with 

 water, in which were abundance of fishes and some molluscs. Some of these 

 cavities also contained sea-snakes from four to five feet long, which were 

 described as having the head hooded like the cobra, do capello, and of a light 

 grey colour slightly speckled. They coiled themselves like serpents on land, 

 and darted at poles thrust in among them. The Singhalese who accompanied 

 the party said that they not only bit venomously, but crushed the limbs of 

 any intruder in their coils." 



A small group of snakes, the members of which are externally very similar to 

 those of the sub-family Dipsadomorphinte in the Colubridtt:, are considered to 



form a family by themselves. From the Dipsadomorphince they 



Blunt-Heads. are distinguished externally by the absence of a groove on the 



Family chin. They resemble the Colubridne in having the maxilhe fixed 



Amblyce2)ha- in a horizontal position, but differ both from that family and 



lidos. from the Viperida by the shortness of those bones in the hinder 



part of the palate known as the pterygoids, which do not 

 extend sufficiently far back to reach either the hinder ends of the lower jaw 

 or the quadrate bone. Both jaws are provided with teeth, all of which are 

 solid, so that these snakes are non-venomous. The slight expansibility of 

 the mouth indicates that they prey upon small animals, while the relatively 

 large dimensions of the eye, in which the pupil is vertical, proclaim nocturnal 

 habits. Five genera of these snakes are known, two, namely, AmblycepJialus 

 and Haplopeltura, being confined to the Oriental countries, whereas Dipsas, 

 Pseudopareus, and Leptognathiis are from Tropical America. 



The last family of snakes is a large one, and includes the vipers, pit-vipers, 

 puff-adders, and rattle-snakes ; all being highly venomous. The essential 



distinctive feature of the Vvperidw is to be found in the fact 



The Viper Tribe, that the short maxillae of the upper jaw are armed with a 



Family pair of large perforated fangs, and can be erected so as to 



Viperidat. become situated at right angles to the plane of the hinder 



portion of the palate. Obviously, this gives to the fangs 

 the most favourable position for inflicting severe wounds. In the viperine 

 snakes the head is always more or less flattened, and is frequently triangular 

 in shape ; while the body is plump and thick, and the tail abbreviated. In 



