126 PERCY SLADEN TRUST EXPEDITION. 
and sand, consolidated together into a soft rock by the droppings of the birds. Above 
was a rich soil composed largely of almost pure guano. Digging into it one found 
countless bones of young and old. The surface of the ground indeed seemed sprinkled 
with the dead, and scarce one young bird out of four could have ultimately survived. 
Guano is no doubt excellent for most plants, but strictly in moderation. On these 
islands we found only ten kinds growing, including the two shrubs already mentioned, 
together with a few Scevola bushes and a single stunted mapou tree (Pisonia). Of the 
rest there was one rush, one true small-leaved succulent and four other herbaceous 
forms. Many were dead, and all were of stunted and fleshy habit with thick roots, 
The Grey-headed Tern (Anous leucocapillus) breeding on tops of bushes at Cargados Carajos. 
adaptations to the peculiar soil. Under these circumstances practically only such insects 
are found as live on decaying animal-matter in the ground, a few beetles, numerous 
cockroaches, earwigs, and crickets gradually burying every dead bird, and finally ants 
and a few flies. Web-spiders were absent, but we got a few jumpers and other predatory 
forms, as well as some centipedes and millipedes. The Scevola bushes were covered 
with green bugs, and while seated for lunch under some coast bushes of the same we 
were attacked and hastily put to flight by large black ticks (Amblyomma loculosum), 
which showed up conspicuously as they crawled towards us over the white sand. The only 
vertebrates were mice and geckoes. On the whole, though at the time we only recorded 
12 species of insects, the collections were of great interest, as showing how extraordinarily 
