94 LIFE : OUTLINES OF GENERAL BIOLOGY 



One of the two giant lizards of the Galapagos Islands, Ambly- 

 rhynchus, is unique in venturing into the sea. Unlike its inland 

 cousin, Conolophus, which has learned to eat the fruit of the 

 prickly- |x?ars. the seashore lizard creeps out on the half-covered 

 rocks, where it holds firm with its twenty claws and browses on the 

 seaweed. Geologically marooned on very inhospitable islands, these 

 giant lizards have obeyed the spur of hunger, and have found two 

 very diverse solutions of their bread-and-butter problem — the one 

 eating prickly-pears and the other the sea-ware. The case of Ambly- 

 rhynchus is peculiady instructive; for it shows how necessity might 

 impt^l a thoroughly terrestrial animal to return to the sea. 



There are no marine amphibians ; and some think it is stretching 

 a point to claim the salmon as a freshwater fish which has returned 



Fig. 26. 



The (fiant Lizard {.\mblyrhynchus), of the Galapagos Islands. After Beebe. 

 It is alxiut four feet long and brilliantly coloured, and also remarkable 

 in its habit of browsing on seaweed on the surf-splashed rocks. 



to the sea for nutritive purposes, a procedure the very reverse of 

 that illustrated by the common eel. So, with a bow to the marine 

 mites and the extraordinary open-sea bugs (Halobates), known as 

 sea-skimmers, we may close the list of animals that have returned 

 to the sea. 



Whenever an animal makes a marked change of habitat, such as 

 passing from land to sea, we cannot but expect special adaptations, 

 and some examples may be of interest. Thus, as to locomotion, 

 though we may not clearly understand how the changes were 

 effected, we see the fitness of the whale's torpedo-shaped body with 

 its perfect stream-lines, its frictionless skin, and the fashioning of 

 the tail into a powerful propeller that does not need to go round. 

 Changes so drastic as these leave many tell-tale evidences, such as 

 the buried vestige of a hip girdle and the dwindled relics of a hind 

 leg ; and they may have required long ages for such regression. It is 

 probable that seals and sea-lions are newcomers to the water as 

 compared with Cetaceans, for the moulding of their bodies and 



