SEA SERPENTS 



lobed liver is really made up of two lobes, though they 

 are closely adpressed. In the same way other organs 

 are contained in other compartments. The lizards' 

 body cavity and viscera suggest a scantily filled and 

 loosely packed portmanteau ; that of the lizard a full 

 and closely packed box. 



Snakes are quite as numerous as lizards, and have 

 much the same range ; they are, like the lizards, parti- 

 cularly abundant in the tropics. Iceland, as we all 

 know, has no snakes, and generally speaking, as with 

 lizards, they wane in numbers towards the north. The 

 three British snakes, viz. the grass snake (Tropidontus 

 natrix), the smooth snake (Coronella aiistriaca), and the 

 viper (Viper a berus), are almost, if not quite, always on 

 view at the Zoo. As with lizards, there are terrestrial, 

 arboreal, aquatic, and even marine snakes. But the 

 marine snakes are much more marine than is the iguan- 

 oid lizard, Oreocephalus, which lives largely in the sea 

 off the Galapagos. Such genera as Distira, Hydrus, 

 Platyurus, are, with a few exceptions, purely marine and 

 pelagic, living at the surface of the ocean and preying 

 upon fish. These snakes are hardly likely, from the 

 nature of the case, to be seen at the Zoo. Besides these 

 marine snakes a large number of serpents of various kinds 

 spend a large part of their time in freshwater ponds, 

 ditches, etc. For example, the North American water 

 viper (Ancistrodon piscivorus), and even the common 

 grass snake. At the opposite extreme is the desert- 

 haunting Cleopatra's asp (Cerastes cornuta), with the 

 projecting and horn-like scale above each eye. Though 

 whether the Egyptian queen did not avail herself of the 

 African cobra (Naia haje) is a moot question. These 

 desert snakes are, like the desert-loving lizards and 

 mammals, and even birds, clad in desert colours. Ar- 

 boreal snakes are exemplified by the boas, and by such 

 types as the green viper, dealt with later. There are 



255 



