IIr ANIMAL LIFE IN THE TROPICAL FORESTS 279 
found, and other tropical countries are no doubt equally rich. 
I will first give some account of the various species observed 
in the Malay islands, and afterwards describe some of the 
more interesting South American groups, which have been 
so carefully observed by Mr. Bates on the Amazons and by 
Mr. Belt in Nicaragua. 
Among the very commonest ants in all parts of the world 
are the species of the family Formicide, which do not sting, 
and are most of them quite harmless. Some make delicate 
papery nests, others live under stones or among grass. 
Several of them accompany Aphides to feed upon the sweet 
secretions from their bodies. They vary in size from the 
large Formica gigas, more than an inch long, to minute 
species so small as to be hardly visible. Those of the genus 
Polyrachis, which are plentiful in all Eastern forests, are 
remarkable for the extraordinary hooks and spines with which 
their bodies are armed, and they are also in many cases 
beautifully sculptured or furrowed. They are not numerous 
individually, and are almost all arboreal, crawling about bark 
and foliage. One species has processes on its back just like 
fish-hooks, others are armed with long, straight spines. They 
generally form papery nests on leaves, and when disturbed 
they rush out and strike their bodies against the nest so as to 
produce a loud rattling noise; but the nest of every species 
differs from those of all others either in size, shape, or position. 
As they all live in rather small communities in exposed 
situations, are not very active, and are rather large and con- 
spicuous, they must be very much exposed to the attacks of 
insectivorous birds and other creatures, and having no sting 
or powerful jaws with which to defend themselves, they would 
be liable to extermination without some special protection. 
This protection they no doubt obtain by their hard smooth 
bodies, and by the curious hooks, spines, points, and bristles 
with which they are armed, which must render them unpalat- 
able morsels, very liable to stick in the jaws or throats of their 
captors. 
A curious and very common species in the Malay islands 
is the green ant (CKcophylla smaragdina), a rather large, long- 
legged, active, and intelligent-looking creature, which lives in 
large nests formed by gluing together the edges of leaves, 
