114 REPTILES AND BIRDS. 



looks like a fola of the skin, pinched and drawn down, the two 

 portions of it being in contact, like a dewlap." It appears that the 

 Cydura also is exclusively herbivorous ; and Mr. Gosse remarks 

 upon the severe wounds it can inflict with its sharply-serrated tail. 

 In general, the larger species of this family are solely vegetable- 

 feeders, while the smaller kinds (such as the Anoles) are more or 

 less insectivorous ; and there are some, of intermediate size, which 

 even prey occasionally upon the kindred Anoles and other small 

 animals. The genera of these Reptiles are exceedingly numerous, 

 as we have seen, and amongst so many there must be considerable 

 variety in the habits ; but we can only notice a very few of them. 

 Within the limited area of the small archipelago of the Gallapagos, 

 situated under the equator about ten degrees west of South America, 

 there are two remarkable species of Iguanidce, of which the habits 

 have been described and commented upon by Mr. Darwin in his 

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

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

 existing Saurian which can properly be said to be a marine animal. 

 In the whole of that group of islands, as he tells us, there is only 

 one rill of fresh water ; 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 Amblyrhynchus, the 

 aquatic sort now constitutes the genus Oreocephalus of Dr. Gray, 

 and it bears the name of O. cristatus. This lizard, according to 

 Mr. Darwin, "is extremely 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, 



