Chap, iii.] INHABITANTS OF THE ROCKS. 63 



the peak. They would not move until actually pushed off the 

 nest. The young, both of boobies and noddies, are very brave, 

 and scream and strike out hard at anything put near them. 

 Our spaniels could not tackle the young boobies, but after one 

 or two pecks fought quite shy of them ; and even the little 

 noddies kept the dogs pretty well at bay, twisting round in the 

 nests and always showing front. Natural selection has no 

 doubt brought about this bravery in the young, to protect 

 them from their constant enemies, the crabs. 



Around all the nests were small flying fish, which are 

 brought by the old birds in their crops, and ejected for food 

 for the young or for the females whilst sitting. Fitzroy visited 

 St. Paul's Rocks on February i6th; Ross on May 29th; we 

 on August 29th; on all these occasions eggs and young birds 

 were found. Hence, breeding goes on all the year round. 



The only other terrestrial inhabitants of the rocks besides 

 the birds are insects and spiders which prey on them. They 

 are most of them to be found by breaking up the nests of the 

 noddies. Darwin* mentions the following : A pupiparous fly 

 {Olfersia), living on the booby as a parasite. This fly belongs 

 to the same group as the curious Nycteribia^ so common on 

 the bodies of fruit-eating bats. The group is remarkable for 

 the fact that the female, instead of laying, like most insects, 

 eggs which produce grubs, produces a chrysalis, from which 

 the fly in a short time emerges. 



A Staphylinid beetle {Quedius), a tick, a small brown moth, 

 belonging to a genus which feeds on feathers, and a wood-louse, 

 living beneath the guano, and spiders, complete Darwin's list. 

 We found two species of spiders, which cover the rock in some 

 places with their web, and in addition to the insects noted by 

 Darwin, the larva of a moth, apparently a Tortrix, and a small 

 Dipter. Von Willemoes Suhm also found a Chelifer, but could 

 not find either the beetle or wood-louse. 



Besides these there are of course to be reckoned the lice, 

 parasites usual upon the two birds, and the list of air-breathing 

 inhabitants seems then complete. 



St. Paul's Rocks being close on the equator, the sun was 

 extremely powerful, and the white guano-covered rocks reflected 

 the radiant heat-rays with the same effect as does a snow surface 

 in Switzerland. Our faces were severely sunburnt. At the 

 base of the " Booby's hill " is a flat expanse of rock with tide 

 pools upon it, in which were shoals of small fish, a black and 

 yellow banded Chcetodon and numerous small gobies. The 

 sides of the pools were covered with a grey Palythoa, a sea 

 anemone, forming colonies of the same species apparently as 



* Darwin, "Journal of Researches," p. 10. 



