9 



HELLER 



beaches, their dark colors harmonizing well with the black basaltic 

 rocks. In some localities they occur so numerously as to more or less 

 completely hide the rocks near the beach. 



Their food consists chiefly of marine algae, both Chlorophyceae 

 and Phaeophyceae, which is obtained by diving in quiet coves and 

 lagoons. In such sheltered places they can usually be seen cropping 

 the algae from the rocks which pave the bottom. After partaking 

 of a sufficient quantity they return to the beaches and crowd upon 

 the bowlders near shore where they spend most of their time basking 

 in the sunshine. 



They seldom go far out to sea, usually remaining within a hundred 

 yards of the beach. None were seen in the open channels between 

 the islands and it is probable that they do not usually leave the island 

 on which they were reared. When attacked they slip lazily into the 

 water, but soon return to the land which they regard as the safest place. 

 Their chief enemies are the sharks ( Car char rhinus) which patrol 

 the shore line and act as checks to the migration of the species. The 

 remains of Amblyrhynchi were not uncommon in the stomachs of 

 the sharks we dissected. It is probable that the Galapagos hawk, 

 Buteo, eats the young when first hatched as in the case of the young 

 of Testudo. 



The eggs are deposited at the end of the rainy season in the sand 

 near the beach, usually in bowlder- strewn places. A nest found at 

 Iguana Cove, Albemarle, and from which the female was driven was 

 situated in the sand which partially filled a fissure in the lava rocks 

 bordering the beach. The eggs in this nest were six in number, soft- 

 shelled, elliptical and measured approximately three inches in length 

 by one and a half in diameter. 



Much individual variation occurs, especially in size and coloration 

 together with a slight amount of local variation. In coloration 

 the variation extends, on nearly every island, from black specimens 

 through brownish to greenish-mottled and to a combination of mot- 

 tlings of all three colors. The young are uniform black above, the 

 mottled coloration not being attained until they reach a length of a 

 foot or more. The immense specimens at Iguana Cove have little 

 black on them, the general coloration above being greenish and 

 brownish blotches. The variation in size among adults is considerable 

 but difficult to determine. The convexity of the head plates and the 

 height of the dorsal crest varies from the smooth condition and low 

 crest of the young to the sharply conical plates and high crest of the 

 old adults. 



