ies that attacked them when the mothers
flew away. I was hard put to it myself to keep these flies, large as
pennies and as flat, from eating me alive. They slipped up my sleeves
and trousers and their bite made a wasp-sting pleasure by comparison.

By rushing into a flock of _rabihorcados_ I succeeded several times in
catching one in my hands. And spreading it out, I made guesses as to
width from tip to tip of wings. None were under seven feet; one measured
all of eight. They made no strenuous resistance and regarded me with
cold eyes. Every flock that I put to flight left several dozen little
ones squalling in the nests; and at one place an old booby waddled to
the nests and began to maltreat the young _rabihorcados_. Instincts of
humanity bade me scare the old brute away until I happened to remember
the relation existing between the two species. Then I watched. With my
own eyes I saw that grizzled booby pick and bite and wring those poor
little birds with a grim and deadly deliberation. When the mothers, soon
returning, fluttered down, they did not attack the booby, but protected
their little ones by covering them with body and wings. Conviction came
upon me that it was instinctive for the booby to kill the parasitical
_rabihorcado_; and likewise instinctive for the _rabihorcado_ to
preserve the life of the booby.

A shout from Manuel directed me toward the extreme eastern end of the
island. On the way I discovered many little dead birds, and the farther
I went the more I found. Among the low bushes were also many old
_rabihorcados_, dead and dry. Some were twisted among the network of
branches, and several were hanging in limp, grotesque, horribly
suggestive attitudes of death. Manuel had all of the Indian's leaning
toward the mystical, and he believed the _rabihorcados_ had destroyed
themselves. Starved they may very well have been, but to me the gales of
that wind-swept, ocean desert accounted for the hanging _rabihorcados_.
Still, when face to face with the island, with its strife, and its
illustration of the survival of the fittest, all that Manuel had claimed
and more, I had to acknowledge the disquieting force of the thing and
its stunning blow to an imagined knowledge of life and its secrets.

Suddenly Manuel shouted and pointed westward. I saw long white streams
of sea-birds coming toward the island. My glass showed them to be
boobies. An instant later thousands of _rabihorcados_ took wing as if
impelled b