RANGE OF VISION IN SOME ARANEIDA. 657 
As a mater of fact, spiders will often let flies—which certainly 
are as M. Forel has said, both stupid and imprudent—not only come 
within two centimeters of them, but climb upon them, and walk 
all over them, practically putting their heads into the lion’s mouth, 
and yet will seem unconscious of their existence ; perhaps they are 
not hungry.” My observations, when in the field, have always 
impressed me with the idea that the Citegrade were endowed with 
considerable length and keenness of vision, and the experiments I 
have made, with a considerable number of individuals of the genera 
Lycosa and Dolomedes, have certainly strengthened that view. On 
one occasion, when digging in my garden, I noticed a Lycosa 
godeffroyi, L. Koch, capture a beetle that was fully 3 inches away, 
and what made this feat the more remarkable was the fact that a 
small tuft of grass lay between it and its prey ; likewise Dolomedes 
neptunus, Rainb., detected, at a considerable distance, prey that 
in colour bore a strong resemblance to the sea-wrack, amongst 
which it was hunting. These facts prove that M. Plateau, when 
he arrived at the conclusion that the vision of the Lycoside was 
“very bad,” did so upon insufficient data. Nevertheless, one 
would not feel disposed to criticise an author upon solitary 
instances, such as I have detailed, were it not for the fact that. 
others, equally as conclusive, have been noted. As far as my 
experience goes, I have always found that whether in captivity, 
or in the full enjoyment of liberty, the Citigrade can, and do, see 
prey at a much greater distance than two centimeters. 
For the purpose of testing the range of vision of these interest- 
ing creatures, I procured a box 15 inches long and 8 inches broad, 
and covered the bottom with paper that had been ruled off into 
inches. A specimen of Lycosa godeffroyi was then placed therein, 
and kept without food until the following day, when a beetle was 
introduced and placed at a distance of 6 inches from the spot 
whereon the spider was resting. Fora few seconds the spider 
remained perfectly quiet, during which time the beetle had 
increased the distance by nearly an inch and a half. At length 
the Arachnid seemed aware of the presence of prey, and commenced 
to move towards it, slowly at first, but afterwards rapidly, and 
having secured it, conveyed it to a corner, where it devoured its 
meal. This experiment was repeated on several occasions and at 
varying distances, but the spider always made direct to the spot 
where the prey happened to be. By this means I was able to 
satisfy myself that Lycosa godeffroy: could see faintly at 8 inches, 
and distinctly at 5. 
With Dolomedes neptunus I have made similar experiments, 
and with equally convincing results. Furthermore, rude imita- 
tions of insects never failed to attract, at a distance of 5 inches, 
when the spiders were hungry, proving, as has been asserted by 
Peckham, that these spiders are influenced, not by scent, but 
2T 
