196 A NATURALIST ON THE "CHALLENGER 



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gums where they are few in number : towards the head of the 

 harbour, and under the natural arch, they have enormous 

 rookeries of their own, where, singularly enough, a few of the 

 Eock-hoppers nest as guests amongst them ; they have large 

 rookeries also in Heard Island, where their eggs are gathered in 

 large quantities by the sealers for eating. The sheath-bills are 

 as abundant here as at Marion Island, but they are larger and 

 heavier than are the birds of that island, and seem to form a 

 sub-species. They will be again referred to. 



During our stay at Kerguelen's Land, we put into several 

 harbours on the coast. At Aldrich Sound I found a cave in the 

 sea-clirT fronting Ship's Channel and under Mount Bromley. 

 The cave had been formed by the excavation by the waves of 

 the volcanic rock, which had been altered, and rendered more 

 yielding at this spot by the intrusion of a dyke which had 

 destroyed the tenacity of the rock by its heat. The dyke which 

 was a narrow one, and almost vertical in direction, was inclined 

 a little, at one part of its course, so as to form the roof of the 

 cave on one side. 



The cave was long and tunnel-like. The " Pock-hopper " 

 penguins breed in this cave. I went into it about forty yards 

 until it was quite dark ; the penguins retreated still before me. 

 I had no means of getting a light to explore the cave further. 

 The small penguin of New Zealand (Sphenisctcs minoi^) has been 

 observed breeding in like manner in the inner chamber of a 

 dark cave * and this mode of nesting is in keeping with the 

 usual habit of this species and others of breeding in deep 

 burrows, which are of course quite dark. 



About Betsy Cove and Poyal Sound, to the southward the 

 valleys are broader, and there is more open flat land than there 

 is around Christmas Harbour, and there are thus here large 

 expanses covered with vegetation. 



At Betsy Cove we stayed about ten days surveying the 

 surrounding district. The Cove is also called Pot Harbour, 

 from there being an old broken iron pot on the beach, a whaler's 

 t ry pot, used for boiling down blubber. As we came into the 

 harbour and anchored, though not more than a quarter of a 

 * "Trans. N. Zealand Inst.," Vol. II, 1868, p. 75. 



