IGUANAS. 123 



volume of the " Voyage of H.M.S. Beagle" One of them is 

 particularly so, because, as that naturalist observes, it is the only 

 existing Saurian which can properly be said to be a maritime 

 animal. In the whole of that group of islands, as he tells us, there 

 is only one rill of fresh water that reaches the coast ; yet this 

 reptile frequents the sea-beaches, and no other parts of the islands. 

 He adds that it is the only known -existing Lizard that feeds 

 exclusively on aquatic productions. Although he refers both 

 species to the genus Amblyrkynchus, the aquatic sort now con- 

 stitutes the genus Oreocephalus of Dr. Gray, and it bears the name 

 of 0. cristatus. This Lizard, according to Mr. Darwin, " is ex- 

 tremely common on all the islands throughout the archipelago of 

 the Gallapagos. It lives exclusively on the rocky sea-beaches, 

 and is never found at least, I never saw one even ten yards 

 inshore. It is a hideous-looking creature, of a dirty black colour, 

 stupid and sluggish in its movements. The usual length of a full- 

 grown one is about a yard, but there are some even four feet long. 

 I have seen a large one which weighed twenty pounds. On the 

 island of Albemarle they seem to grow to a greater size than on 

 any other. These Lizards were occasionally seen some hundred 

 yards from the shore swimming about ; and Captain Colnett, in 

 his ' Voyage/ says, ' they go out to sea in shoals to fish.' With 

 respect to the object, I believe that he is mistaken ; but the fact 

 stated on so good an authority cannot be doubted. When in the 

 water the animal swims with perfect ease and quickness, by a 

 serpentine movement of its body and flattened tail the legs, 

 during this time, being motionless and closely collapsed on its 

 sides. A seaman on board sank one, with a heavy weight attached 

 to it, thinking thus to kill it directly ; but when an hour after- 

 t wards he drew up the line, the Lizard was quite active. Their 

 i limbs and strong claws are admirably adapted for crawling over 

 } the rugged and fissured masses of lava which everywhere there 

 ! form the coast. In such situations, a group of six or seven of 

 : these ugly reptiles may oftentimes be seen on the black rocks, 

 1 a few feet above the surf, basking in the sun with outstretched 

 ; legs. I opened the stomachs of several/' continues Mr. Darwin, 

 " and in each case found it largely distended with minced sea- weed 

 : of that kind -which grows in thin foliaceous expansions of a bright 



