58 
Tigri is wild in the extreme. The river is broken up into a number 
of channels, and between are islands of various sizes overgrown with 
bushes, past which, and over which in times of flood, as on the occa¬ 
sion of my visit, the water swirls by. At Tumatumari I was intro¬ 
duced to the genial gold officer, Mr. A. K. Menzies, who, when he 
heard I was a visitor, invited me to go to the Potaro Station, further 
up the river, and back from the waterside, some twelve miles. This 
sounded excellent, and the following morning, after having viewed the 
grand Tumatumari Cataract from all points of vantage, we started in 
the miniature launch huddled together with eight or ten swarthy 
niggers. The river was fairly down ” this morning, and the launch 
could only make two miles an hour. Through one of the rapids, 
although the engine was going as if it would burst, the launch would 
not move, and it became necessary to unhitch a boat we were towing, 
put some of our black passengers therein, and try again. We now 
crawled through, and the niggers, having pulled the other boat along 
by overhanging boughs, joined us again. 
The Potaro landing was reached, and, having got the loan of a 
springless two-wheeled cart, a start was made for the next stage of the 
journey. The road is “ a corduroy,” made with small tree trunks laid 
crosswise, and the travelling is not devoid of motion. Here,at last, T said 
to myself, I should find insect life abundant and probably somewhat diffe¬ 
rent, as we were now 170 odd miles from the coast. After eight miles 
had been accomplished my friend decided to go and ask for lodging 
at the house of one of the two other white men who live in this place. 
Next morning we decided to walk the remaining four miles to the 
Government station. Here prac tically the whole of the remaining col¬ 
lecting was done. The opening day was heralded with the capture of 
some nice Theclids, amongst others, but what was most gratifying was 
to see some insects swarming. Melinaea nineine, M. era wen, Ceratinia 
rallmia, ( '. reritabilis, Mel. eyina , Lycorea pasiniintia and L. ceres, to¬ 
gether sometimes covered the white blossoms of a plant growing along¬ 
side the roadway. The similar colouring of all these different insects 
could not but strike one. These colours—brown, yellow, and black- 
form quite the commonest colouring of the insects of Guiana, and it 
is now pretty well agreed that it has come about by the influence of 
mimicry, those brown, yellow, and black species that were distasteful 
remaining as types to which numbers of other species have converged 
by a process of natural selection. Although the enemies are, and 
must be, very numerous to bring about such a state of things, they are 
not by any means in evidence. Soft-billed birds are rarely seen, and 
the struggle must be kept up by lizards and such like creatures. The 
absence of birds, particularly song-birds, is most noticeable. The 
parrots, toucanos, and macaws one hears occasionally screeching over¬ 
head, high up among the branches of the tallest trees, but such a thing 
as a song-bird is foreign to these woodlands. Is it possible we here 
again have evidence of the terrible competition for life in these forests? 
Can it be that what might be song-birds are too engaged in looking- 
after their safety, and, also, might not their song reveal their presence 
to some of their enemies? Such queries as these suggest themselves 
as being within the, realm of possibility, after what one sees going on 
with the lepidoptera. Botanically, also, the struggle is keen, if not 
keenest of all, although in quite a different way. Might, here, is 
what is most needed; the strongest wins. The cases where lepidop- 
