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 Amblyrhynclms, the aquatic sort now con- 

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

 of O.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- 

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

 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, 

 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 



