656 PROCEEDINGS OF SECTION D. 
Laterigrade, or “ Crab” spiders, usually conceal themselves 
amongst herbage, the bark of trees, rocks, and walls, whence they 
sally forth to capture prey, a habit which would point to a toler- 
ably long range of vision, but which was not satisfactorily estab- 
lished by experiment, although at close quarters their eyesight 
appeared to be very keen. For instance, prey placed at a distance 
of 3 inches from one of these spiders (Stephanopsis altifrons, Camb. } 
failed to attract attention ; but, when the distance was reduced to 
3, an inch, the insects were ‘instantly seized. This was tried several 
times with unvarying results. Another experiment was that of 
tying a silk thread to a living but maimed insect, which was placed 
at about 1 ¢ Of an inch from the spider. Immediately the latter saw 
the i cca it made a rush to seize it, but was compelled to make 
chase, the insect being pulled quickly away from it. An occasional 
jerk, made for the purpose of increasing the space between the 
spider and the insect, appeared to confuse the former, for it would 
stop and move, now to the right and then to the left, as though 
in search, and, failing to locate it, seemed disposed to give it up ; 3 
but, upon the bait being placed, practically, ‘ under its nose,” 
resumed the chase. Such was the result of several experiments 
with Stephanopsis altifrons, Camb., and Cymbacha saucia, L. Koch, 
put I do not claim that as sufficient evidence in denoting the limit 
or extent of the range cf vision in spiders of this group. It is 
interesting as far as it goes, but before the question can be settled 
with regard to the Laterigrade, many experiments, spread over 
not only a wide collection of species, but also individuals, must be 
made before we can arrive at a definite conclusion. 
That the Citigrade possess a long range of vision has been 
proved by such eminent writers as Simon, McCook, and Peckham. 
McCook says, ‘He has seen a young Dolomedes sexpunctatus 
leap the side of a box and catch a fly on the wing, and return to 
its perch by the rebound of its drag-line. Such an act not only 
shows ability to see, but also some faculty to estimate distance, 
unless we suppose it to have been a chance shot.” On the other 
hand, Felix Plateau says that “ After experimenting with a small 
number (tive) of species, that the sight of two large groups of 
spiders, the Attidw and the Lycosidee, is very bad, the limit of 
clear vision being about two centimeters.” In their interesting 
paper on “ The Sense of Sight in Spiders,”* Dr. and Mrs. Peckham 
give several quotations from Felix Plateau’s papers on ‘ The Sense 
of Sight in Arthropods,”t from which they conclude—and rightly 
so, I think—that his experiments ‘show not how far the spider 
can see distinctly, but at what distance it usually seizes its prey” 
and they argue that “‘it is not safe to take for granted that if the 
spider does “not try to catch the fly, he, therefore, does not see it. 
* Trans. Wisconsin Acad. of Sci., Arts, and Letters, vol. x. f 
+ Recherches Expérimentales sur la Vision chez les Arthropodes, Deuxiéme partie, 
