358 Wisconsin Academy of Sciences, Arts and Letters. 
abdomen with metallic luster appears in another species, P. pic- 
ata, but here it is on the upper, not the under, surface. If the 
female is not interested in these matters it is an odd chance that 
in this case the position is reversed, the abdomen being held 
vertically upward during courtship. 
On the vitality theory the intense color and the peculiar 
growths and appendages should be distributed over the body in 
relation only to anatomical structure and should appear behind 
as often as in front, on the legs of the fourth pair as often as on 
those of the first. If, then, we find that the male is especially 
beautified in those parts that are brought plainly into view 
when he meets the female we shall have reason to believe that 
there is some latent meaning in their distribution. As a matter 
of fact the ornaments of the male in the Attidse run along cer¬ 
tain lines. Leaving the genera in which the two sexes are alike 
and beginning with those that are least modified we can trace a 
gradual increase in the amount of sexual color. Zy gob alius and 
Dendryphantes have snowy bands or silvery scales on head 
and clypeus, and their falces are frequently burnished and 
elongated. In their display they often fling the palpi out hor¬ 
izontally, or fold them under, so that they do not obstruct the 
view of these parts. P. picata, in addition to his metallic ab¬ 
domen, has steely blue iridescence on the upper surface of the 
first leg, which is enlarged and flattened. In his display he 
holds his front feet firmly on the ground so as to bring the 
shining upper surface to the front, lifts his abdomen, and thus 
placed sways from side to side. 
We now come to Icius and Anoka. In these graceful spiders 
the white legs are delicately lined or spotted with black or are 
fringed and tufted; the front eyes have colored rings around 
them, or piquant tufts, like eyebrows, above, and they are often 
clothed in rosy and golden scales. The display of the male ex¬ 
hibits these charms and is enhanced by whirling dances and 
waving plumes. In Phidippus we find the ornamentation tak¬ 
ing new and striking forms on head, face, clypeus and falces, 
and becoming very elaborate on the first legs where there are 
single fringes, double fringes of contrasting color overlapping 
