384 
special study of Mimicry before going on my Expedition and I have 
no time to do so now either. But I venture to think this an ad- 
vantage for the observations recorded; they are made by an entirely 
unprejudiced mind, interested only in the phenomena themselves, 
not in the pro's or contra's of these much discussed biological 
problems. 
The observations almost exclusively relate to Insects; only once, 
on Luzon, near Manila, I observed a curious case of agressive 
protection in a spider. In a white flower with transparent yellow 
stamina I found a spider with the body coloured white, exactly 
like the petals, and the legs clear and transparent, exactly like 
the stamina. It was very hard to distinguish the spider, and evi- 
dently the insects visiting these flowers must fall an easy prey to 
it. — Unfortunately I-had nothing to preserve the spider in, and 
there was no opportunity to visit the place later on, so I cannot 
say anything about the name of this spider. Exactly the same color- 
ation was observed by Alcock (Op. cit. p. 204) in a species of 
Mantis found in the flowers of Pancratium. 
Excepting this single case all the observations here recorded 
were made in Panama, especially on the little island Taboga, 
where I spent the months November 1915—February 1916. 
When walking in the woods I often observed like a shade pas- 
sing by very rapidly. That it was an insect, was plain enough, 
but it took some time before I succeded in securing a specimen. 
It proved to be a Hymenopterous insect of the Pompilidæ (Agenia 
sp.) with white spotted wings and long thin legs, ringed with black 
and white, It is this coloration which, combined with the slender 
and elongate legs and the very easy flight, makes it almost impos- 
sible to distinguish the insect when flying. The same observation 
was made in regard to a large Tipulid; in this case it worked 
also when the insect was sitting on a tree-trunk (-— it always 
alighted on mossy, gray tree-trunks —); the legs were then. con- 
stantly in a rapid shivering motion up and down, which made it 
very hard to find the insect, if one had not carefully noted the 
exact spot, where it alighted.") 
— ROSE the flies I noticed one form (Calobata lasciva Fabr.) 
BEG: Wesenberg: Lund, in his delightful book ,Insektlivet i Ferske 
Vandef, 1915, p. 331, gives a vivid description of similar observations 
on Tipula gigantea and Pedizia rivosa. 
