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OBSERVATIONS ON SEXUAL SELECTION

SPIDERS OF THE RAMILY ATED,

GEORGE W. AND ELIZABETH G. PECKHAM.

1889.

-- ENGRAVERS AND PRINTERS. -----~

OBSERVATIONS ON SEXUAL SELECTION IN SPIDERS
OF THE FAMILY ATTID.

GEORGE W. AND ELIZABETH G. PECKHAM.

Introduction.

Mr. Wallace, in his well known essay on Colors of Animals,
remarks that color per se may be considered normal and needs
no special accounting for; that amid the constant variations
of animals and plants color is ever tending to vary and to
appear where it is absent; and that natural selection is con-
stantly eliminating such tints as are injurious to the species
while it preserves and intensifies such as are useful; and in
opposition to Darwin he has argued that the sexual diversity of
color, common in many animals, has its primary cause in the
special need of protection for the female, which represses in
her the bright colors that are normally produced in both sexes
by general laws. Or, to put it in another way, he starts with
the fact of the variability of color in animals of both sexes
and says that in the female, where greater protection is needed,
the color is toned down or eliminated, while in the male, the
need for protection being less, the color may be preserved and
intensified. Mr. Wallace has supplemented this theory by
another factor; he now holds that the frequent superiority, to
use his own words, of the male bird or insect in brightness or
intensity of color, even where the general coloration is the
same in both sexes, is primarily “due to the greater vigor and
activity and the higher vitality of the male) * * * This
intensity of coloration becomes most developed in the male dur-
ing the breeding season when the vitality is at a maximum.
* * * The greater intensity of colors in the male, which
may be termed the normal sexual difference, would be further
developed by the combats of the males for the possession of the

+

4 PECKHAM. [Vol. 1.

females. The most vigorous and energetic usually being able
to rear most offspring, intensity of color, if dependent on or cor-
related with vigor, would tend to increase. But as differences
of color depend upon minute chemical or structural differences
in the organism, increasing vigor acting unequally on different
portions of the integument, and often producing at the same
time abnormal developments of hair, horns, scales, feathers,
etc., would almost necessarily lead also to variable distribution
of color and thus to the production of new tints and markings.
These acquired colors would * * * be transmitted to both
sexes, or to one only, according as they first appeared at an
early age, or in adults of one sex; * * * but in all cases where
an increasing development of color became disadvantageous to
the female, it would be checked by natural selection; and thus
produce the numerous instances of protective coloring in the
female only, which occur in these two groups, birds and butter-
abies.”

We have here two theories offered to explain sexual differ-
ences in color: the first is, that natural selection modifies
color in the female for purposes of protection; and the second,
that color may be produced or intensified where there is a sur-
plus of vital energy, as in male animals generally, and some-
times in the females, and more especially at the breeding
season. We will here consider the second theory, since Mr
Wallace regards this as the more important in making intel-
ligible cases of more brilliant coloring in the male as compared
with the female.

What is meant by an excess of vital energy is not quite
clear. Does this term imply that the colored modifications of
the integument represent the excess of nutriment over expen-
diture? This seems scarcely probable, and yet what other
interpretation is to be put upon such a statement? Supposing
this interpretation to be correct, if the color or development of
plumage represents the surplus over ordinary expenditure,
should not the least active animals, rather than the most vigor-

1 Tropical Nature, pp. 187 and 193-196.

No. 1.] SEXUAL SELECTION IN SPIDERS. 5

ous, have the greater surplus and consequently the richer orna-
mentation ?

Grant Allen, in his Colour Sense, remarks, concerning the
ornamental appendages of animals: “Whatever we may think
of their functions, we must agree that they are, on the whole,
products of a high vitality. They represent part of the excess
of nutriment over expenditure. But these dermal adjuncts do
not probably take away anything from the effective energies of
the organism.”* He evidently understands Mr. Wallace to
mean that these color adjuncts are by-products, or waste, from
the other tissues. In this connection he quotes from Mr. Lowne
to the effect that “the dermal appendages of reptiles and the
feathers of birds, rich in pigment and nitrogen, are probably
entirely excrementitious to the other tissues, and, without
doubt, depend in great part for their origin on the solid nature
of the excretion of the kidneys. Birds especially, leading a
very active life, excrete material rich in nitrogen; and the
feathers, which are shed periodically, enable them to throw
off that element without overtaxing their renal organs.”°

“Hence,” says Mr. Allen, “we can understand why the more
active and energetic sex should possess a greater number of
highly developed dermal adjuncts, and should often display
much brighter colors than the females.” This, however inter-
esting 1t may be as a speculation, has, so far as we are aware,
no direct evidence to support it; and knowing so little as we
do at present of the functions of the kidneys in birds, and of

1P. 188.

2The fact that closely related species annually undergo a double moult and
others only a single one, and that even in the same species the sexes sometimes
differ in their moulting habits, renders this proposition improbable, The habits
being usually identical, why should one species depend upon moulting for the dis-
posal of its surplus nitrogen, while in another the burden is borne by the excretory
organs alone? Is therea single anatomical fact to countenance such a supposition?
Darwin says that there is reason to believe that with certain bustards and rail-like
birds, which properly undergo a single moult, some of the older males retain their
nuptial plumage throughout the year. In the birds of paradise some have a single
moult, some a double, and others, after the moult of the first year, do not cast
their feathers again. For other facts bearing on this habit, see Descent of Man,
Am. Ed., pp. 391-394.

6 PECKHAM. [Vol. 1.

the nature of the pigment in their feathers, it would be prema-
ture to discuss it in this connection.

Let us see how far the hypothesis that brilliant coloring is
correlated with high vitality is supported by facts. Wallace
makes the activity and pugnacity of an animal the criterion of
its vitality ; and where the male bird takes charge of the eggs and
incubates them, he considers this change of habit, along with
the pugnacity of the female, a proof that in such cases she pos-
sesses the higher vital energy, pugnacity being the important
factor. “Of the mode of action of the general principles of
color-development among animals,”’* he says, “we have an
excellent example in humming-birds. * * * The more
vivid colors, and more developed plumage of the males, I am
now inclined to think may be wholly due to their greater vital
energy, and to those general laws which lead to such superior
developments even in domestic breeds; butin some cases the
need of protection by the female while incubating, to which I
formerly imputed the whole phenomenon, may have sup-
pressed a portion of the ornament which she would otherwise
have attained.” In view of the importance of this point the
following evidence, offered in its support, seems rather meagre.
“The extreme pugnacity of humming-birds has been noticed
by all observers, and it seems to be to some extent proportioned
to the degree of colour and ornamentation in the species. Thus
Mr. Salvin observes of Eugenes fulgens, that it is ‘a most pug-
nacious bird,’ and that ‘hardly any species shows itself more
brilliantly on the wing.” Again, of Campylopterus henvileu-
curus,— the pugnacity of this species is remarkable. It is very
seldom that two males meet without an erial battle,—and ‘the
large and showy tailof this humming-bird makes it one of the
most conspicuous on the wing.’ Again, the elegant frill-necked
Lophornis ornatus ‘is very pugnacious, erecting its crest, throw-
ing out its whiskers and attacking ‘every humming-bird that
may pass within its range of vision ;’ and of another species L.
magnificus, it is said that ‘it is so bold that the sight of man

1 The italics are ours.

No. 1.] SEXUAL SELECTION IN SPIDERS. 7

creates no alarm.’ The beautifully coloured Thawmastura Cora
‘rarely permits any other humming-bird to remain in its
neighborhood, but wages a continual and terrible war upon
them.’ The magnificent bar-tail, Cometes sparganurus, one of the
most imposing of all the humming-birds, is extremely fierce
and pugnacious, ‘the males chasing each other through the
air with surprising perseverance and acrimony.’ These are all
the species I find noticed as being especially pugnacious, and
every one of them is exceptionally colored or ornamented ;
while not one of the small, plain, and less ornamental species
are so described, although many of them are common and well
observed species.” *

Here we have sia species of humming-birds, given as all
that are noticed as especially pugnacious, to establish the wide
generalization that there is a causal relation between high vital
activity, as shown by fierceness and pugnacity, and brilliancy
of coloring, in the family Trochilidx, containing 118 genera and
390 species, of which 340 are brightly colored.’

The large family of pigeons gives evidence that makes
strongly against the theory. Many of them are conspicuously
colored—indeed Mr. Wallace remarks, “in the Malay Archi-
pelago and Pacific islands, they occur in such profusion and
present such singular forms and brilliant colors that they are
sure to attract attention. Here we find the extensive group of
fruit-pigeons, which, in their general green colors, adorned with
patches and bands of purple, white, blue, or orange, almost rival
the parrot tribe; while the golden-green Nicobar pigeon, the great
crowned pigeons of New Guinea as large as turkeys, and the
golden-yellow fruit-dove of the Fijis, can hardly be surpassed
for beauty.”* If the high vitality of the humming-birds will

1 Tropical Nature, pp. 213, 214.

2 Baird, Brewer and Ridgway, WV. A. Birds, say that about fifty species are
plainly colored.

3 Loc. cit. p. 108. All the pigeons build open nests and the males take part in
incubation. In the case of the humming-birds, which also build open nests, Wallace
has abandoned, in part, the factor of protection to the female during incubation,
since, in a number of the most beautiful species, the sexes are alike, and, as Darwin
says, “in the majority the females, though less brilliant than the males, are brightly

8 PECKHAM. [Vol. 1.

explain the unusual development of color in both sexes, and
will sometimes override the action of natural selection in keep-
ing down the brightness of the female, this is evidently not
the case where the pigeons are concerned, since they are not
remarkable for activity nor pugnacity, and are notoriously liable
to destruction by many enemies. The further fact that the
male is more highly ornamented than the female, and yet
assists in incubation, is still more out of harmony with the
hypothesis. That the presence of ornaments or gaudy tints is
not necessarily correlated with high vitality in birds is shown
by the Barbets, which are “rather clumsy, fruit-eating birds,”
and are clothed in green, diversified by the most vivid patches
of. yellows, reds and blues.’

Again, in the birds of paradise there seems to be no rela-
tion between pugnacity and color. Mr. Wallace, in speaking
of the splendid Great Bird of Paradise, which he studied in the
Aru Islands, says that they congregate at “sdcaleli or dancing
parties,” held in certain trees in the forest. “On one of these
trees a dozen or twenty full-plumaged male birds assemble to-
gether, raise up their wings, stretch out their necks, and ele-
vate their exquisite plumes, keeping them in a continual vi-
bration. Between whiles they fly across from branch to
branch in great excitement, so that the whole tree is filled
with waving plumes in every variety of attitude and motion.””
Although these birds were carefully observed not a word is said
of their fighting nor of any display of pugnacity. In regard
to the Red Bird of Paradise, he mentions having kept a num-
ber of the magnificent male birds in the same cage; this he
could not have done had they quarreled to any extent.* He
also mentions “the large cage” of two specimens of the Les-

colored.” Does not the same reasoning hold good with the pigeons and a host of other
birds where the nest is open and the female conspicuous? A fair consideration of the
facts seems to us to confirm Darwin’s supposition that the habit, common with bright
colored birds, of using covered nests was acquired after, rather than before the devel-
opment of the color.

1 Tropical Nature, p. 105.

2 Malay Archipelago, p. 446.

3 Loc, cit., p. 536,

No. 1.] SEXUAL SELECTION IN SPIDERS. 9

ser Bird of Paradise, which he took with him to England, as
though he kept them together.’ If the trait of pugnacity is
so closely related to brilliant ornamentation in the humming-
birds, why should it not not be so in the birds of paradise?
And why do we find brilliant color in many birds that have no
more—indeed rather less—vigor than the soberly dressed birds
of prey? Since, of all living naturalists, Mr. Wallace is un-
doubtedly the most competent to discuss this theory of the
correlation of great vitality and bright color, it is surprising
that he can find so little evidence in its favor.

Perhaps the most difficult fact to reconcile with the theory
is the absence of ornamentation and bright color in the bats.
They have wide expanse of integument, and great activity,
the conditions specified by Mr. Wallace for the development of
gaudy pigment, and nothing, apparently, in their habits to keep
it down; but, except in the frugivorous bats, we find little dif-
ference between the sexes, nor is there any appreciable ap-
proach to bright colors. As Darwin remarks, it deserves atten-
tion as bearing on the question whether bright colors are serv-
iceable to male animals from being ornamental, that only in
frugivorous bats is the sense of sight well developed, and it is

only in this group that we find any color.’

In the Araneides the great number of species and the wide
differences between the several groups in habits and in amount
of ornamentation, offer unusual facilities for testing Wallace’s
two theories of sexual color.

There is a common impression that among spiders
there is little development of ornamentation, and that
they are, as arule, inconspicuous and dull. This is far from
being true. Wallace, in his Tropical Nature, says: “The
small jumping spiders are also noticeable from their im-
mense numbers, variety and beauty. They frequent foliage and
flowers, running about actively in pursuit of small insects ; and
many of them are so exquisitely colored as to’ resemble jewels

1 Loe. cit., p. 557.
2 Descent of Man, p. 534.

10 PECKHAM. Vol. 1.

rather than spiders.”! In the Malay Archipelago, also, he was
struck by the “abundance and variety of the little jumping
spiders, which abound on flowers and foliage, and are often per-
fect gems of beauty.”” Bates, too, in The Naturalist on the Ama-
zon, says that “the number of spiders ornamented with showy
colors was somewhat remarkable. A large collection of spi-
ders from the tropics is sure to contain as great a proportion of
beautifully colored specimens as would be found among an
equal number of birds from the same region. Let us, then, en-
deavor to apply to them the hypothesis, that the brighter color
of the male is due to his greater activity and vital force.
Beginning with the most brilliant family, the Attid, we find
that the females are, with few exceptions, larger, stronger and
much more pugnacious than the males. Some four years ago
we placed two females of Phidippus morsitans together in a glass
jar. No sooner did they observe each other than both prepared
for battle. Eyeing each other with a firm glance they slowly
approached, and in a moment were locked in deadly combat.
Within a few seconds the cephalothorax of one was pierced by
the fang of the other, and with a convulsive tremor it relaxed
its hold and fell dead. We placed together, in all, four females,
and in each instance the fight was short but even to the
death. Subsequently, we put in a well-developed male,
which, though smaller, was compactly built and apparently
strong enough to bring tke virago to terms; but, to our sur-
prise, he seemed alarmed and retreated, trying to avoid her;
she, however, followed him up, and finally killed him. We
have observed the same habits in Phidippus rufus. In Dendry-
phantes elegans the female is nearly a third larger than the
male. During the past summer we kept a number of this
species, males and females, together in a large mating-box, and
were much struck by the greater quarrelsomeness of the
females; they would frequently go out of their way to chase
each other, and they were much more circumspect in approach-

3

1 P.97.
2 Malay Archipelago, p. 437.
3P. 54,

No. 1.] SEXUAL SELECTION IN SPIDERS. 11

ing each other than were the males. In Jcius mitratus neither
sex was especially pugnacious, but the male was as little so as
the female. In Synageles picata the females never came near
each other without some display of hostility, though they did
not actually fight.

In several species of Xysticus—as ferox and gulosus—the
females are savage and ready to attack anything that comes
in their way, while the males are smaller and more peaceable.
De Geer tells of a male spider that, “in the midst of his prepar-
atory caresses was seized by the object of his attentions, envel-
oped by her ina web, and then devoured, a sight which, as he
adds, filled him with horror and indignation.”' The Rey. O.
P. Cambridge holds that the greater ferocity on the part of the
female in the genus Nephila has led, through the action of
natural selection, to the extreme reduction in the size of the
males.” In each of two species of Lycosa, whose mating
habits we were endeavoring to discover, two males were
destroyed by a single female.

Not all female spiders are savage and quarrelsome. In
some genera, as Linyphia, the two sexes live happily together
inthe same web ; but Hentz, after twenty years’ study of North
American spiders, says that “there is less ferocity in the spi-
ders of this division than in any other of the family. It isthe
only sub-genus in which the male and female may be seen har-
moniously dwelling together.”* Although subsequent inyesti-
gation has made it necessary to qualify this statement, the

1 Kirby and Spence, Entomology, Vol. 1, p. 280, 1818.

2 Proc. Zool. Soc. 1871, p. 621. Simon has the following interesting remarks on
sexual differences in size in Epeiride: “Dans les genres ot l’inégalité est faible, le
nombre des males parait égal & celui des femelles, car 4 l’époque de l'amour ces Hpeir-
ide se rencontrent réguliérement par paires; mais, daus les genres ou il y a grande
disproportion, le nombre des males est beaucoup plus considérable, car il n’est pas
rare de voir quatre on cing individus dece sexe courtiser une seule femelle. Ces petits
males sout adultes les premiers, mais la durée deleur vie parait trés-courte, car aprés
lVépoque de la reproduction ils disparaissent complétement; ils ne construisent point
de toile propre; mais ils se tiennent 4 proximité des endroits habités par la femelle,
attendant le moment propice pour l’accouplement, quia lien au milieu dela toile de
celle-ci est qui est tonjours précédeé de longues hésitations. Les Arachnides de France,
I, p. 20.

3 Spiders of the United States, p. 132.

12 PECKHAM. [Vol. 1,

broad fact remains that, as a rule, the females are more power-
ful and more pugnacious than the males. Walckenaer, Menge,
Hentz and others give numerous instances where the male
meets his death through the fierceness of his mate; in fact, the
danger is so imminent that after mating it is the habit in sev-
eral genera (Hpeira and Tegnaria are mentioned by Walckenaer)
for the male to retire with precipitation from the web of the
female, asa reasonable precaution. ‘The relations between the
sexes have been admirably characterized by Romanes in Ani-
mal Intelligence, where he says: “In many species the male spi-
der in conducting his courtship has to incur an amount of per-
sonal danger at the hands (and jaws) of his terrific spouse
which might well daunt the courage of a Leander. Ridicu-
lously small and weak in build, the males of these species can
only conduct the rites of marriage with their enormous and
voracious brides by a process of active manceuvering, which, if
unsuccessful, is certain to cost them their lives. * * * There
is no other case in the animal kingdom where courtship is
attended with any approach to the gravity of danger that is
here observable.”?

It might be supposed that in spiders the usual conditions
are reversed and that, as in some birds, the females are more
beautifully colored as well as more pugnacious than the males.
This, however, is not the case. Even where the coloration of
the two sexes is similar the tints of the male are usually
brighter; and in many cases, especially among the Attidx, the
female is dull-colored, while the weak and unaggressive male is
extremely brilliant.

There is a family of spiders, the Gasleracanthidx, compris-
ing a number of genera and several hundred species, widely
distributed and very rich in individuals. In the whole order
of spiders there is no group where the females are so univer-
sally remarkable for inactivity and sluggishness of movement.
After the web is made she remains, nearly all the time, stand-
ing motionless in the center. ‘he males, so far as they are

1P. 204.

No. 1.] SEXUAL SELECTION IN SPIDERS. 13

known, are smaller and much more active in their habits.
Contrary to what we should expect on the theory, however, the
males are, as compared with the females, inconspicuous aud
plainly colored; the females being almost always strikingly
and often very brilliantly adorned with black, yellow,
red, blue and white. If it be objected that the Gastera-
canthide do not entirely meet the point in question, since
their colors have been developed as a warning of their inedi-
bility, there are scores of edible species among the web-build-
ing spiders which are brilliantly colored and, at the same time,
are very inactive; as in the genera Hpeira, Meta, Tetragnatha,
Theridium, Linyphia and others.

Turning to the family Lycosidx, with its numerous species,
just the reverse appears, since it is among these vagabond or
wolf-spiders that we find the most vigorous species, ever run-
ning about and full of restless activity. We know a good deal
of their habits and of the courage of the females in defending
their young; but, contrary to what we should expect, this family
presents very little color development, dull grays, browns and
blacks prevailing. The Agelenide are very active in their move-
ments, throwing themselves upon their prey with great vigor,
and depending upon their strength, and not upon web-lines, to
hold it, even when it is large and powerful. These spiders are
also dull colored.

The spiders, then, seem well adapted to disprove the prop-
osition that there is a causal relation between vital activity and
color development, since in the sedentary groups, while many
of the species are plainly colored, there are nearly as many that
present the most beautiful tints; and, on the other hand, some
of the wandering and very active groups are, for the most
part, clothed in sombre hues.

Turning to the other question, how far have the females
had their color toned down, as compared with the males, for
purposes of protection during the nesting period? If we ex-
amine the Attide, where there are marked differences in the col-
oration of the sexes, we find that all the females remain under

14 PECKHAM. [Vol. 1,

a thick, web-like covering, with their cocoons, until the eggs
are hatched—that is to say, all the species of this family
have covered nests. Many of these covered nests are occupied
by dull-colored females, the males of the same species being
showily attired. The same is true, to a great extent, among
the Thomisidx, where the females, often protectively colored,
remain near the eggs in a covered nest. ‘The protectively col-
ored Lycosidx, it is true, have practically open nests, as they
usually carry the eggs about with them. In other families the
habits vary, some leaving the eggs to their fate as soon as the
cocoon is formed, while others give it much or little attention,
as the case may be. A general survey of the facts shows no
relation between color development in the females and their
nidifying habits, and it is highly probable that in spiders, as in
birds, the color was developed prior to the formation of these
habits.

We must, then, seek further for an explanation of sexual
coloring in spiders, since here we have present to account for
it neither special vitality on the part of the male, nor need of
protective coloring, while nidifying, in the female.

MOULTING HABITS.

There is no group of facts that brings out the remarkable
similarity between birds and spiders in color development
more prominently than that which is gained from a study of
the moulting habits of the two classes. In spiders, as in birds,
the young very often differ from the adults, and in many spe-
cies where the sexes differ when adult, the male being the
brighter, they are alike until they reach maturity, when the
male, along with his sexual development, acquires his brilliant
color. Cuvier formulated, under several rules, the various
changes that the plumage of birds undergoes from the nestling
to the adult. These rules were extended by Blyth; and Dar-
win, in The Descent of Man, not only amplified and added to
them, but also submitted them to a thorough analysis and dis-
cussion in order to discover the causes of the phenomena. In

No. 1.] SEXUAL SELECTION IN SPIDERS. 15

looking over systematic works we unfortunately obtain little or
no information about the moulting habits of spiders. Most of
the species have been described by workers living in the large
cities of Europe, from collections coming to them from distant
parts of the world, so that an observation of habits was impos-
sible. Then, too, such collections contain only adult or nearly
adult forms, since both systematists and collectors have thus
far given their attention only to these. There are, therefore,
accessible on this subject, little more than the impressions of
several high authorities in arachnology as published by Darwin.
For some years past we have been accumulating data as to the
differences in form and color between the young and the adults,
and also between the two sexes in the adult stage in the same
species.

Before giving the facts that we have thus far obtained it
may be well to remind our readers that spiders, shortly after
hatching, cast the skin, and that this moulting of the integu-
ment, including the outer coat of the eyes, is repeated, the
number of times varying in the different species and possibly
in the two sexes. Itis probable that the Afiide moult from
seven to eleven times before reaching maturity. In Dendry-
phantes capitatus we have counted ten moults and the spider was
still immature. If one examines any of our spiders soon after
they are hatched he will verify Dr. McCook’s generalization
that “the color of young spiders is almost without exception
bright yellow or green, whitish or livid.”’ Soon after this stage,
probably at the third or fourth moult, colors appear, distrib-
uted in patterns characteristic of the species, and as the spiders
continue to advance in age and make their successive moullts,
still other and more marked changes may be noted.

Let us now pass to the consideration of the classes of cases
under which the differences and resemblances, in color and
form, between the young spiders and the adults of one or both
sexes may be arranged. It is true among spiders as among
birds, that the several classes pass into each other; and that

1 Proc. Acad. of Nat. Sci. of Phila., 1888, p. 172.

16 PECKHAM. [Vol. 1,

when the young resemble their parents, the resemblance,
although very strong, is not so complete as to render them
exactly alike.

CLASSES OF CASES.

I. When the adult male is more conspicuous than the
adult female the young of both sexes in color and form closely
resemble the adult female.

II. When the adult female is more conspicuous than the
adult male the young of both sexes, in color and form, more
closely resemble the adult male than they do the adult female,
especially in the earlier moults.

IIT. When the adult male resembles the adult female the
young of both sexes resemble the adults.

In Darwin’s discussion of the subject of sexual selection,
he considered in great detail how far the moulting habits of
birds tended to support his theory that the differences between
the two sexes are attributable to female selection, rather than
to natural selection acting upon the greater need for protection
on the part of the female. In his profound discussion of the
laws of heredity he formulates two general propositions. First:
That variations appearing early in the life of an organism
would tend to be transmitted to the offspring of both sexes.
Second: That variations appearing late in life would be limited
to the sex in which they first appeared, and would tend to ap-
pear at a corresponding age; the exception being that they
might appear at an earlier age in the offspring than they did
in the first instance. When the great complexity of the sub-
ject is considered, and the way in which natural selection must
have sometimes modified sexual selection is taken into account,
it is remarkable how fully the moulting habits of birds con-
firm his generalizations; and it is of the highest interest to in-
quire how far the moulting habits of spiders are also consistent
with them.

Class I includes the cases where the adult male spider is

1 These classes are slightly modified from Darwin, Descent of Man, p. 466.

No. 1.] SEXUAL SELECTION IN SPIDERS. 17

more conspicuous than the adult female, the young of both
sexes resembling the adult female, both in color and form—or,
at least, resembling her much more than they do the adult
male. A good example of this class is Phidippus johnsonii,
where the female has the abdomen red and black, with a white
base and some white dots, while that of the male is bright
vermillion red with sometimes a white band at the base. The
young of both sexes resemble the mother until the last moult,
when the males assume their bright livery. Philzus militaris,
avery common Aftus, is another illustration ; in the male the
cephalothorax and abdemen are bright bronze brown, the former
with a wide, pure white band on each upper side and a white
spot on the center of the head, the latter with a wide, white
band around the base and sides; the female has a brown body
covered over with white and gray hairs, which form a more or
less distinct pattern of lines and spots. To give a better idea
of this difference, let us suppose a male bird with the body,
neck and head bright bronze brown, and the wings and a patch
on the head pure white, with a female having mottled white
and brown plumage.

Hentz described the female of his Plexippus puerperus as
a different species under the specific name sylvanus, so little do
the sexesresemble each other. Dendryphantes capitatus is another
species in which there are great sexual differences. As in the
last instance, the male and female were described by Hentz as
different species. We may suppose that the sexual peculiari-
ties of the male have been only recently acquired in capitatus,
since he sometimes retains the markings and color of the
female, these being proper to him in the immature stage. In
Icius palmarum the sexes are very different. We shall, later on,
describe the differences in the face and falces, so that here it is
enough to say, that in the male the whole body is bronze
brown, covered with short, golden down, while in the female
the color is rufus, with black and white markings.

For Habrocestum splendens the colored figures of the moults
and the adult forms (Plate I) bring out the fact that while the

18 PECKHAM. [Vol. 1.

young are not exactly like the adult female they resemble her
much more closely than they do the adult male. This is one of our
most beautiful males. The highly iridescent scales, which cover
the entire body, make it impossible to give, in a painting, a
correct idea of its brilliancy, since the color changes in every
light. The male only gets this gorgeous livery at the last moult,
just as he becomes mature, though in some species the nuptial
robe is acquired one moult before maturity.

The family Aftidx, from which these illustrations have
been taken, is by common consent, placed at the head of the
order, and contains among its 1,500 species the greatest amount
of sexual difference and the highest development of ornamen-
tation ; indeed, as we have seen, Wallace speaks of them as re-
sembling jewels rather than spiders, and Walckenaer says that
their species are well marked by the rich diversity of their
colors and the variety of the designs which ornament their
abdomens.”

In the seventy-eight species described in our work on the
Altide of North America we have both male and female in
only forty ; or, to be more accurate, we have felt warranted in
placing males and females together in only forty instances.
Doubtless in many cases we have separated the two sexes, mak-
ing two species out of one, but the difference in color is so great
that, without knowledge of their habits, no other course was
possible.? Of the forty species, we know the moults of thirty_
two, and of these, nineteen species form a group characterized
by marked sexual differences, the males being very generally
conspicuously colored as compared with the females, while in
others only the falces are different. Since the nineteen species
represent twelve important genera’ it would seem that so far as
the North American Attide are concerned, the generalization is

1 Hist. Nat. des Insectes Apteres, I, p. 481.

2 We have, in the genus Phidippus, sixteen species, four pairs, four single males
and eight single females. P. cardinalis, male, is of a splendid, uniform, cardinal
red; to which of the eight plainly attired females he belongs we do not know; and we
have the same difficulty in other cases.

3 Phidippus, Phileus, Plerippus, Dendryphantes, Icius, Habrocestum, Astia,
Zygoballus, Synageles, Menemerus, Lyssomanes, and Epiblemwm

No. 1.] SEXUAL SELECTION IN SPIDERS. 19

well established. If we may add to these a large number of
bright-colored, undescribed species from our own Guatemala
collection, in which the young closely resemble the female, the
generalization is materially strenghtened.

In order to estimate to what extent the sexes differ in the
Attide, we tabulated the species, in a number of works, giving
the number of species in which both sexes, and also the num-
ber in which one only are described. If it may be assumed
that a collector ordinarily takes as many of one sex as of the
other—and our numerous collections from different parts of the
world confirm this supposition'—if the sexes were fairly alike
they would be identified as one species and placed together ; if,
on the contrary, the sexual differences were great (the habits
being unknown) many species would be founded on a single
sex.

TABLE OF SPECIES DESCRIBED BY DIFFERENT AUTHORS, ACCORDING
TO SEX. TOTAL 930.

AUTHOR. LOCALITY. $&Q| 6 Q
Koch and Meyeerlns: AUR REIT, Ceo oo paneer edaeade 48 47 57
Taczanowski.. a South America............... 60 PA | 26
j {|World, except N. Am. and)
Oe KOON Sconces na06 | Europe De Neier eee NE f 3 49 46
Cambridge ........-- WEEMOWS,...cdeo0'n ceeadaccoaccc0 16 27 16
Lucas........ oakondD é UNI ETGTES. o aan agcasoncossooour . 8 13 36
§|Burmah and Indian Archi-}
funoueill er (ll men CLAS O orotate lor dni svcictere lorerara i) iW 62 | 42
SLM ONE aay eles sis ‘ Various places, not Beane, ‘ 8 47 | 22,
§|World, except N. Am. and}
Walckenaer........ | Europe. is ae Re j 3 11 17
IReckiham-s anes eee ae NOLAN Cr Calan <eiiele erates 40 17 21
SiiGiss coossonoouced MAN yaanoogo des doodaeroounee 94 28 on
VWHNGOMN oe ososceosease Madagascar, Mauritius, etc. . Ss oo
297 328 306

The table shows that in a total of 930 species from all parts
of the world the single males just about balance the single

1 That this is not always true in other families is shown by Stoliczka, who says:
“In collecting Hpeiride I was particularly struck with the very great scarcity of male
specimens; for, among about 200 specimens belonging to about thirty species, there
were not more than five or six males.” Indian Arachnida, Proc. Asiat. Soc., Vol.
XXXVI, p. 284. This was probably due to his having collected either before or after
the mating season, when the males are always more rare.

20 PECKHAM. [Vol. 1.

females, and that the same is true, with a few exceptions, in the
individual collections. Excepting when the spiders are well-
known, as in the case of Simon’s Attide of France, a compari-
son of the description of the two sexes, when they have been
put together, would only serve to show a similarity between the
males and females, since it would be only in the species where
there was little or no sexual difference that they could be placed
together. Where they are well-known, as in the Aftidx of
France, we find by such a comparison that in thirty-nine species
the male is plainly unlike the female, being in twenty-six in-
stances much more conspicuous, while in fifty-five the sexes are
similar, or, if they differ, the male is no more conspicuous than
the female. These facts are given to make it clear that the
sexes very commonly differ, the male being brighter than the
female. It is probably not too much to say, that in the Attide,
at least two-fifths of all the species have the male more conspic-
uous than the female. .

Menge’, in referring to the greater brilliancy of the male of
Micromata ornata, says that it only assumes its bright color as
a “bridal adornment,” and in this connection makes the state-
ment that in the families Thomisidx and Salticide the males are
generally more beautifully colored than the females. We have,
in North America, several Thomiside that are like Menge’s
species in the difference in color between the sexes, and also in
that the young males are like the female, and only assume
their bright color at the last moult. Darwin remarks on the
fact that “the female of Sparassus smaragdulus is dullish green,
whilst the adult male has the abdomen of a fine yellow, with
three longitudinal stripes of rich red;” while young this male
resembles the female. ‘The obvious conclusion from these facts
is that it is the male that has varied, and this, too; late in life,
so that his peculiarities, having been limited to one sex, do not
appear in the young. We are not embarrassed in this group
by any need on the part of the female for plain colors to pro-
tect her during incubation, since, without exception, the cocoon

1 Preussische Spinnen, II, p. 396,

[No. 1.] SEXUAL SELECTION IN SPIDERS. 21

is so placed as to be concealed, or, as in the Aftide, is covered
with a thick layer of web, under which the mother spider re-
mains until the young appear, seldom leaving the nest to ob-
tain food. On the whole, the explanation of sexual differences
of color in spiders which is most conformable with facts, is that
the males have departed from the usual colors of the genus,’
and that most probably this departure has been brought about
by sexual or female selection.

Thus in the Habrocestum group the general coloring of the
genus is represented by the females of cristatwm and auratum,
which are gray, with oblique whitish bands; in vwiridipes there
is atendency to greater concentration of color, and consequently
to stronger contrast, the color being blackish with yellowish
white bands. In peregrinum and auraiwm we find that the
males have gone still further in the same direction, the ground
color being deep black and the bands pure white. (Plate1.) In
splenders the male has made a still greater departure from the
typical coloring of the genus, while the female, also departing
therefrom, though not in so great a degree, shows the strongly
contrasting black and white that is found on the males of
peregrinum and auratum.

Class 1. When the adult female is more conspicuous than
the adult male, the young of both sexes, both in color and
form, more closely resemble the male than they do the female,
especially in the earlier moults.

This class, while it is found both in spiders and birds,
differs widely in the two groups, both in the number of in-
stances and in the causes that have produced them. While in
birds the number of cases in which the females are brighter is

1 This is the opinion of Blackwall and of Canestrini. Thorell,inspeaking of the
genus Hrigone (of the family Theridide, a genus that contains an immense num-
ber of species, says: ‘“‘The study of the spiders belonging to this interesting genus
has hitherto been comparatively neglected, and this neglect is no doubt to be
attributed partly to their diminutive size, and partly to the great similarity prevail-
ing among the females of the different species. * * * Many a female is sometimes
mated with one, and sometimes with another male; * * * the following lists of
synonyms must, unless the contrary be directly stated, be considered as applying
only to the males, which are comparatively easily distinguishable.” Remarks on
Synonyms of Hurop. Spiders, p. 97.

22

PECKHAM. [Vol. 1.

inconsiderable, and while even in these cases the female is but

little more conspicuous than

Fig. 1.—Gasteracantha rufospinosa.
Upper figure, male enlarged seven times;
lower figurer female, enlarged four

times (from Marx.)

Fig. 2.—Gasteracantha crepidophora, female

(from Cambridge.)

the male, in spiders there are
numerous species in which the
female is decked in the most
gaudy hues, her body being at
the same time protected by
strong, sharp spines, while the
smaller male is unarmed and
comparatively inconspicuous.’
(Figs. 1 and 2.) The spiders
to which we refer belong to the
genera Gasteracantha, Acrosoma,
Phoronocidia and others, includ-
ing possibly 250 species distri-
buted over all parts of the
world. The differences between
the males and females are shown
in Plate III. Only a few males
are described in this group, but
they all agree in the peculiari-
ties mentioned.

The perplexing fact in
this connection is that
while the females at first
resemble the males, it is
only while they are quite
young, since when they
are from a quarter to a
third grown they begin to
assume the adult form
and color, and it seems as
though characteristics de-
veloping so early should
have been transmitted to

1A seeming exception to this rule is G. Cowani, ¢, describedin Proc. Zool.
Soc., 1882, p. 766. As this case was sufficient to invalidate our generalization we wrote
to Mr. Butler, asking him to re-examine the spider in question to make sure that it

No. 1.] SEXUAL SELECTION IN SPIDERS. 23

both sexes. After a good deal of consideration we are
inclined to believe that in the early history of the group
the male and female both possessed some such form and
color as is now seen in the adult male, and in the first few
moults of the female; and that afterwards the adult female,
probably on account of some change in habits, varied toward
her present size, form and color under the action of natural
selection. “As variations occurring late in life,” says Darwin,
“and transmitted to one sex alone, have incessantly been taken
advantage of and accumulated through sexual selection in re-
lation to the reproduction of the species; therefore it appears,
at first sight, an unaccountable fact that similar variations have
not frequently been accumulated through natural selection, in
relation to the ordinary habits of life. If this had occurred
the two sexes would often have been differently modified, for
the sake, for instance, of capturing prey or of escaping from
danger. Differences of this kind between the two sexes do oc-
casionally occur, especially in the lower classes. But this im-
plies that the two sexes follow different habits in their struggles
for existence, which is a rare circumstance with the higher
animals.”*

The other supposition open to us, namely, that the varia-
tion from the male form began in young females and were sex-
ually limited from the first, is improbable, in view of the mass
of evidence that variations before maturity are inherited by
both sexes equally. The habits of the female, standing nearly
all the time exposed in the web, give the clue to the occasion of
her modification. The habits of the male being different, he
is left unmodified ; he is usually found in less exposed posi-

was amale and not afemale. Mr. Pocock, who is now in charge of the Arachnida in
the British Museum, responded as follows:
BRITISH MusEUM (Natural History), LONDON, March 238, 1889.
R * * * * * *

You are quite right in supposing that Mr. Butler fell into error in describing
his specimens of this species as being males. They are in reality females. The
distal segments, however, of the palpi are considerably wider than the preceding, and
no doubt the mistake arose from a superficial examination of this appendage.

1 Descent of Man, p. 241,

24 PECKHAM. [Vol. 1.

tions, and only for a few days, at the mating time, is to be seen
in the web.

Class III. When the adult male resembles the adult
female the young of both sexes resemble the adults.

The greater number of species in this class have dull col-
ors, which seem to be protective, as in the Lycosidx, many of the
Drasside, Epeiride, Thomiside and others. The same problems
are presented here that are so ably discussed by Darwin in the
case of birds belonging to this class. It seems likely that in
the orb-weavers a large part of the courtship is conducted by
vibrating the web lines, and that the males depend upon their
skill in this direction, and not upon color alone, in attracting
the female. The modifications of the first pair of legs, so com-
mon in the male spiders of the group, might be explained as
useful in producing variations in these vibrations. We have
some little evidence on this point, but defer consideration of it
until treating of mating habits. In the Attidx, when the male
is not strikingly colored, it is more than probable that the
choice of the female is determined by his antics and grace of
movement. Saitis pulex is a good example. While in the
greater number of instances in this class the colors are dull, we
have many species which are brilliant. hus, in the genus
Homalattus, many of the species have metallic greens or lovely
iridescent blues or violets, while others are soft brown,
mottled with white. We have not enough data to throw any
light on the very intricate problems here presented, and can
only refer the reader to Darwin’s work,’ where the whole sub-
ject is admirably discussed. If, therein, he will substitute
spider for bird, whenever the latter word appears, he will see
how full of difficulty is the whole subject.

We have other cases that come under several classes, but
as the instances are few, we will simply describe them indi-
vidually. In Hasarius hoyi the adult male is more conspicuous
than the adult female, which, indeed, was first described as a
separate species under the name pinus. The young, very early,

1 Loc. cit., p, 481.

No. 1.] SEXUAL SELECTION IN SPIDERS. 25

differ from each other according to sex, the young males resem-
bling the adult males, and the young females the adult females.
In this case the law of inheritance at corresponding ages must
be supposed to have failed, the young males inheriting their
differential peculiarities at an earlier age than that at which the
variation first appeared in their male ancestors.

Phidippus rufus, when mature, is a brick-red spider, the
male being considerably brighter than his consort. When
about one-seventh grown, and after the third or fourth moult,
the young are very dark brown, with light yellow legs. Some
moults later, they are reddish, with narrow, oblique whitish
bars on the sides of the abdomen, and two dark bands on the
dorsum, on each of which is a row of white dots. The appear-
ance of the spider changes but little during the next four
moults, but after the last—the tenth—both male and female
become mature and acquire the adult color. The meaning of
the fifth moult—that with the uniform brown body and yellow
legs—we are unable to explain. The appearance of the female
after the fifth moult is similar to that of many other females
in the genus, and her final change is probably due to a trans-
ference to her of the male color, which, judging from the
moults, must have appeared late in life.

All the cases under the first and third classes are intelli-
gible if we suppose that the females have selected the more
conspicuous males, and that when variations occurred late in
life they were limited to the sex in which they first appeared.
There are, however, many cases in which it is probable that the
color variation of the male has modified the female in a greater
or less degree, and this accounts for the instances in which the
female, as well as the male, is showily colored, especially since
the showy color in these females usually tends to approach the
coloring of the males, and to depart, in the same proportion,
from the normal coloring of the genus. The second class, in
which the females are more brilliant than the males, is the
only one in which the moulting habits of spiders are not strik-
ingly similar to those of birds; and it seems in the highest

26 PECKHAM. [Vol. 1.

degree probable that where there is so close a resemblance
between two such complex sets of phenomena, in widely
separate classes, they can only have been brought about by a
common cause.

SECONDARY SEXUAL CHARACTERS.

It is a noticeable feature in the secondary sexual peculi-
arities of spiders, beside those of color, which have already
been sufficiently dwelt upon, that they are very commonly
found in the falces, clypeus, palpi and first pair of legs—that is
to say, in those parts of the animal that are plainly in view
when the male is paying court to the female; and it is a fact
of great significance that even in the species where sexual dif-
ferences are reduced to a minimum we usually find a modifi-
cation of one or more of those parts which serve to render
the male somewhat more conspicuous or showy than the
female. Synageles picata is a case in’ point, the sexes being nearly
alike, but the male having the first legs flattened and brilliantly
iridescent. In several species of the genus Liyssomanes the sexes
only differ in the length of
the falces and that of the first
pair of legs or palpi.

The antlike spiders are
notable for differences in the
falees of the two sexes. Sal-
ticus formicarius, (Fig. 3), a
common European species, is
a good illustration, the female
having short, vertical, red-
dish black faleces, while those
of the male are horizontal,
Fig. 3.—Salticus formicarius (from C. much enlarged, and copper

Koch.) Right-hand figure, male; left-hand E 3
figure, female. green incolor. In an ant-like

spider from Australia, Synemosyna lupata, (Fig. 4, see p. 27), Dr.
Koch describes a very curious development in the falces of the
male; their great length, their teeth, and their branching

1 Lyssomaues viridis, jemineus and amazonicus.

No. 1.] SEXUAL SELECTION IN SPIDERS. 27

fangs, reminding one of the great mandibles in certain male
Incandz. The female is undescribed, but we know, in this
genus and in others closely related, so many males that have
enlarged falces while those of the
female are short, that this, too, is
doubtless a sexual characteristic.’
Cambridge has described two spid-
ers from Ceylon? which are remark-
able for the great elongation of the
male falces, these being in both
species longer than the cephalotho-
rax, while the fangs are toothed and
equal in length to the falx. In both
species, too, the falces seem to be
attractively colored, as in one they
are “dark black-brown and shining,”
and in the other “very slightly and
transversely rugose, and shining in
some lights with an opaline hue.” It _ Fig. 4—Synemosyna lupata.
is true in many males that the ace
falces are not only greatly enlarged but are also brilliantly
colored; and in this connection it is of high importance to note
that the brightly colored hairs or metallic scales, as well as the
protuberances, are either on the anterior surface, or in some
way so placed as to be plainly in view from in front.

In a common spider of the Southernand Eastern United
States Jcius palmarum Hentz we have a good illustration.
In the male the falces are compressed and horizontal and are
three times as long as the face, the fang equaling the falx in
length. The front surface of the falces isdark bronzy rufus and
on each outer edge isa wide band of snowy white hairs. In

1 We have examined 49 species of ant-like spiders, but in no instance have we
found a female with long falces, while we know of 19 males in which they are much
lengthened. One might have expected to find that an occasional female had inherited
the modification from the male, but it seems to be, in this group, strictly limited to
one sex.

2 Ann. and Mag. of Nat. Hist., 1869, pp. 68-70.

28 PECKHAM. [Vol. 1.

the female the falces are vertical and only as long as the face,
the fang being equally reduced, and the white hairs are absent.
The male is rendered still more striking by the long, snowy
white hairs which cover his clypeus, while the forehead and a
space just below the first row of eyes is covered with bright
red hairs. All this ornamentation is lacking in the female,
and the contrast between the showy male and his modestly
attired mate is very striking. In the little cosmopolitan zebra
spider, Hpiblemum scenicum we find the same difference in the
size of the falces of the two sexes, the male
having them four times as long as the face,
while in the female they are only one-and-a-
half times as long. Dr. Koch, in his magni-
ficent work Arachniden Australiens, figures and
describes an Attus Opisthoncus abnormis (Fig. 5),
with curiously formed falces. Their general
color is yellowish brown, but the front surface
is coppery red, and toward the imner edges
they are of a pretty, iridescent, bronzy green;
but nature, less generous to the female, has
given her only some white hairs over her small

and unmodified yellowish brown falces. For
abniotints ron Le ee of offense or defense, however, the
face and falces ot female fang is the more effective of the two,
as mal bila ol and our fine fellow doubtless hopes more from
a his beauty than his strength.

In the sub-family etragnathine the falces are long in
both sexes, but longer and much more ornamented with vari-
ous processes and bunches of hair in the male than in the
female." (Figs. 6 and 7, see p. 29.) The two figures fairly
represent this greater development in the one sex than in
the other.

Canestrini remarks on the sexual differences in the falces,
saying: “Sometimes they are long and strong, with fine teeth,

1 This point has also been noted by J. H. Emerton, New England Epeiride, p.
298. He says of the Telragnathine: ‘The mandibles, especially in the males, are very
long, and toothed on the inner edge.”

No. 1.] SEXUAL SELECTION IN SPIDERS. 99

in the male, while in the female they are short, weak and with-
out teeth.”* He also speaks of the entirely different colors of
the male and female falces of the same species. Not infre-
quently there are two forms among the
males of a species, one with long and mod-
ified falces, and another having them
short, and more like those of the female.
In Pensacola signata, an Attus from Guate-
mala, we have two such forms. To quote
from a former paper of our own: “Inthe \
first, which is a little the larger, the falces

are more than twice as long as the face, y,(2" fom meenatha gral:
slightly retreating, narrow at the base and SEA ncienAT ime OE Gh
extremity, but dilated in the middle when sate

looked at from in front. Near the anterior inner edge, in the
middle, is a strong apophysis or spime in each falx, which
reaches nearly to the end of the fang; fang long and slightly
bent. In the second form the falces are relatively shorter, and
are but very little dilated
in the middle, so that the
curve on the inner edge is

not marked, and the spine
is less than half as long as
in the first form. We find
others intermediate be-
tween these two extremes.®
Canestrini also refers to the
existence of two male

= Fig. 7.—Tetragnatha straminea (from Hmer-
forms, and explains them ton). Left-hand figure, falx of male; right-hand

figure, falx of female.

by the supposition that we
here see these secondary sexual characteristics, as it were, in

process of development.*
Another curious modification is found in Icius cornutus,

1 Oaratteri sesswali secondarii degli Arachnidi, Atti della Soc. Vento—Tren-
tina di Sc. Nat. Padova, I, Fasc. 3, 1873.

2 Loe. cit.

3 On Some New Genera and Species of Attide, G. W.anud E. G, Peckham, Proc.
Nat. Hist. Soc. of Wisconsin, 1887, p. 84. Pa

4 This occurs in Phileus militaris, Icius palmarum, and Zygoballus bettini.
Canestrini mentions the genera Linyphia, Theridium and Dysdera,

30 PECKHAM. [Vol. 1.

from Madagascar, where there is long projection from the an-
terior face of each falx, the two processes extending forward and
looking a little like a pair of horns; they are more than halfas
long as the cephalothorax.’

The height of the clypeus°? was formerly used in the class-
ification of Attide, but it has more recently been found to be
so entirely a sexual peculiarity, as to be of little or no
taxonomic value. It is frequently adorned by colored hairs,
which fall over the falces, or is diversified by curious patterns
formed by bars and patches of down. The very striking ap-
pearance that a spider presents with this feature well developed
is shown in Titanattus s«vus,a male from Guatemala. In a
common North American spider, Dendryphantes
capitatus, (Fig. 8), the clypeus of the male is con-
spicuously marked by several white bands; one

passes up between the anterior middle eyes from

ae np he the base of the falces; and two on each side pass
phantes capitate: back over the cephalothorax. The contrast
and palpi (from between these snowy white bands and the dark
color of the rest of the face is exceedingly strik-

ing. The female has the whole clypeus whitish and is not at

all conspicuous. In two species of Habrocestum, coronatum and
cecatum, the clypeus is covered with bright red hairs. In de-
scribing H. coronatum, Hentz says that “the bright scarlet spot
on its front gives to this spider a whimsical air of fierceness,
which is heightened by its attitudes and singular motions.” *
In Thorellia ensifer, the male has two bunches of stout dark
hairs projecting forward from just above the insertion of the
falces, which are not present in the female.* Hyllus pterygodes*
has the clypeus, or rather what might be called the cheeks, drawn

1 On Some New Genera and Species of Attide from Madagascar, G. W and E.
G. Peckham, Proc. Nat. Hist. Soc. of Wisconsin, p. 31.

2The clypeus is all of the face above the insertion of the falces and below
the first row of eyes.

3 North American Spiders, p. 65.
4 Koch and Keyserling, Arachniden Australiens, p. 1353.

5 Id ibid., p. 1339.

No. 1.] SEXUAL SELECTION IN SPIDERS. 31

out and gradually coming to a point on each side, so that the
face looks, from in front, very much swollen and enlarged.
This surface, in both sexes, is covered with bright scales which
are somewhat rosy in tint, and the points at the sides are furn-
ished with some stout dark hairs.

In examining the upper part of the face, just above or be-
low the first row of eyes, a number of interesting features may
be observed. In one section of the sub-family Lyssomanee most
of the species have, for the general color of the body, a tender
grass green. In this group the clypeus and the region around
the first row of eyes is nearly always adorned with a covering
of red hairs, which are sometimes dull, sometimes very bright;
this ornamentation is not usually confined to one sex, but in L.
amazonicus the red is perceptibly brighter in the male, while
though in Asamonea puella the eye-region of the female shows
no red hairs, the male has the forehead covered in the middle
by thick, silvery white, and on the sides by reddish hairs, his
clypeus, also being unusually high.

The other section of this sub-family often presents dark
colors, and here the clypeus and eye-region are more frequently
marked with white pubescence or metallic scales than with red
hairs; thus in 4A. fenwipes the dark clypeus of the male is cov-
ered with highly iridescent scales, and that of the female is
light yellow, covered with thick, snowy white hairs.

The bright markings in some of these species have evi-
dently been transmitted to the females through ing
the males. Looking at the group as a whole, it is °@Q°
important to note how frequently the adornment
is so placed upon the body as to be brought into
view when the spiders face each other.

In Amycus micans, (Fig. 9), of which only the
male is known, the face is very high, and all its
parts are covered with glittering violet, green and fig. »—Amyeus

micans. Male,

golden scales; above the first row of eyes is a face and _tfalces
x (from L. Koch).

transverse band of scale-like hairs, some few
longer hairs growing out between ; this band is shining, colored

32 PECKHAM. [Vol. 1.

like the rest of the face. Amycus tristriatus has a high face,
the hairs around the eyes being white in the lower half and
yellowish red above.”

In the nine species of the genus Amycus described by the
two Kochs, we have only males; in the South American spiders
of this genus described by Simon and Taczanowski,’? we have
both sexes in four species, and in three of these the clypeus of
the female is low; in the fourth it is said to be “rather high.”
The great height of the clypeus in Amycus is, in fact, a sexual
peculiarity, although in some instances
it may have been transmitted to the
female.

By far the most remarkable instance
of facial adornment is to be foand in
Mopsus mormon* (Fig. 10.) The face of
the male is dark brown, covered with
steel-blue scales; around the eyes are
both brown and yellowish red hairs; the
front of the long falces is also dark
brown, covered with bright metaltic
scales; and to add to his beauty there
is a high vertical ridge of variously tinted
hairs extending over his forehead. The

Fig. 10.—Mopsus mormon Part above the middle eyes is brown, but
abo andltalesgene icles on either side it changes to pure white,
ing ridge of hairs; lower 5 o 6
figure, face and falees of gradually becoming yellowish as it passes

back on to the sides. In the female, while
the general coloration is the same, the most striking orna-
ment—the band of hairs—is entirely absent. In this species
we are reminded of the wonderful crests found in humming-
birds and fruit pigeons. In Dendryphantes elegansthe male alone
has two oblique converging ridges of short hairs extending from
the eyes of the second row to the anterior middle eyes; and in

1 Koch and Keyserling, loc cit., p. 1173.

2 Id ibid., p. 1181.

3 A. rufifrons, Simon; A. fusco manus, A. mystacalus, A. scops, Taczanowski.
4 Arachniden Australiens, p. 1319, described as Ascyltus pencillatus.

No. 1.] SEXUAL SELECTION IN SPIDERS. 30

the black male form of Astia vittata there are three long tufts of
black hairs on the eye-region, which are absent not only in the
female but also in the other male form.

Leaving the Aitidx, there are several genera described by
Menge, Cambridge, Simon, Thorell, Emerton and others that
illustrate curious sexual modifications of the upper part of the
face. For example, in the genus Argy-
rodes, (Fig. 11), of Simon, while the
head of the female is often high and
somewhat notched in front, in that of 47 ._
the male each of these divisions of the §\. 4
front part of the head gives rise to a
horn, covered at the extremities with
hairs. The drawing shows the parts
in the two sexes. Emerton in New
England Therididx, when speaking of
the genus Ceratinella says: “The heads
of the males are usually higher than
those of the females, and in some ,<i% 17 Srevrodes areynodes

Zonas mon): uae figure,
species are very large and raised into figure, cephalotharax of female.

figure, cephalotharax of female.
humps ;” and of the genus Cornicularia

- hesays that “the males have a hump or horn on the front of the
head between the eyes, usually ornamented by flat, stiff hairs.
In several species there are two horns, the lower one being small
and partly concealed by the upper.” There are many other
genera in this family, with large numbers of species distributed
over different parts of the world. Most of these species are
small, but close inspection shows a great deal of sexual differ-
ence in the head parts and often also in the falces.

In male spiders the palpi are modified and serve as organs
for the conveyance of the sperm cells to the epigynum of the
female. Beside this direct use in the reproductive act they
often play an important part as ornamental appendages. The
female palpi, are, speaking generally, cylindrical, five-jointed
outgrowths of the maxille, covered with hairs and varying
somewhat in length and color; but throughout the order there

34 PECKHAM. [Vol. 1.

is but little difference among the variousspecies. Passing over
the many and great differences of structure in the last or tarsal
joint of the male palpus, which are primary sexual characters,
we find, in this organ, many curious modifications of form and
of ornamentation the only use of which is to please the
female.'

In some species they are greatly elongated (Lagnus longi-
manus); in others there are curious enlargements and apophy-
ses on one or more of the joints (Plexippus puerperus); but the
most frequent and by far the most striking form of decoration
is a covering of long white or yellowish hairs which gives them
a plume-like appearance (Pensacola signata).

In many spiders the sexes differ not only in the beautiful
plumose palpi of the male, but also in the locomotive organs.
The legs of the first pair are lengthened, in many males, and
the several joints are enlarged and brilliantly colored, or fur-
nished with long hairs or iridescent scale-like sete. In no
family of spiders does sexual selection seem to have been more
effective than in the Attidz. Many of the species, as we have
seen, are furnished with remarkable falces, elaborate head or-
naments and plume-like palpi, and we have now to give an ac-
count of a further modification which has apparently been
gained for the sake of ornament, or possibly through the sham
battles between the males.

In an ant-like species, Synageles picata, the female has legs
of the ordinary form ; but in the male the tibia of the first leg
is enlarged and flattened, and the anterior face of the enlarge-
ment is of a brilliant, steel-blue metallic color, as glossy as the
breast of certain pigeons. In Phileus metallescens, from Aus-
tralia, the legs of the first pair in the male are 11 mm. long,
while those of the female are only 9 mm.; those of the male
are of a very brilliant steel-blue color, and are ornamented
with rings, spots and fringes of short, scale-like hairs, and of

1 Koch and Keyserling in Arachniden Australiens describe in the family
Attide thirty-four males having well developed fringes or tufts of hair on the palpi,
while there are only five females so ornamented, and several of these to only a mod-
erate extent.

No. 1.] SEXUAL SELECTION IN SPIDERS. 35

long, white hairs; those of the female are but slightly iridescent,
and lack all further ornament. In Dendryphantes elegans the
first lee in the male has on the lower half of the tibia a wide
fringe of hair, which is very conspicuous as he waves his legs
while courting; while the legs of the female are plain. These
leg modifications have been frequently transmitted to the
female, so that not uncommonly we find both sexes presenting
striking forms, which are, however, proportionately less re-
markable in the females than in the males. For example, in
Diolenius phrynoides, where the first legs are wonderfully length-
ened and modified, those of the femal® measure 121 mm., and
those of the male 20} mm., being nearly twice as long. The
curious change in the legs of this species so impressed
Walckenaer as to make him suggest that the spider must walk
on the water, since in no other way could such legs be useful.
As it isa land species-his explana-
tion must be abandoned, and we are
constrained to look upon these legs )'¥
as secondary sexual organs, useless \¥
for locomotion, but of high import-
ance while mating. To gain a clearer
idea of this lengthening of the first
legs one has only to imagine that in
some group of human beings the
arms of the men were doubled in
length, while in the women they
remained as before. There are nu-
merous species in this genus, all
characterized by their long legs (Fig.
12). Itis not unusual for female as
well as male beetles to possess well
developed horns and knobs, so that

Fig. 12. _—Digieaine venustus
there is nothing anomalous in the (from nature). Upper figure, male;
lower figure, female.

elongated legs of both sexes of the Dio-
lenii. In Chirothecia, a South American genus of Attide, we meet

with other instances of modified legs, but here there isa marked

36 PECKHAM. [Vol: 1.

difference between the sexes, the males having the legs longer,
more robust, and more ornamented than the females. This is
also true in the North American species Icius palmarum. Satis
barbipes has the third leg of the male fringed with hairs on
either side, which gives it quite a plume-like appearance, while
that of the female is entirely plain. In an undescribed species
of Habrocestum from Arizona the first leg of the female is plain,
while that of the male has on the tibia a fringe of long, silky,
yellow hairs, mingled with which are other hairs, which are
enlarged and flattened at the end. These spatulate hairs also
appear on the first legs of Habrocestum hirsutum; in this species
we have only the male.

Walckenaer remarks that his earlier division of Attidz into
Sauteuses, or short-legged, and Voltigeuses, or long-legged, is
vicious, since in many species of Sauteuses the males have very
long legs, and are, therefore, if we have not seen the female,
placed in the Voltigeuses, while the females must be put into the
Sauteuses.' We may go further than this, and say that all these
modifications of the legs are sexual and of little or no import-
ance in taxonomy.

The instances which we have given of secondary sexual
differences might have been indefinitely multiplied, but we
have only thought it necessary to give examples of each kind
or class of modification ; these will serve, we trust, to establish
the fact that these differences are not less numerous among
spiders than among birds and insects.

MATING HABITS.

For a number of years prior to 1888, we had been much
impressed by the many important differences between the
sexes of our jumping-spiders, and since we thought it most
probable that they had come about through sexual selection,
we had often tried to watch them during their courtship, but
up to that time with very little success. We had occasional
glimpses of their habits, but they were so incomplete as to con-

1 Loc. cit., p. 482.

No. 1.] SEXUAL SELECTION IN SPIDERS. 37

tribute but little to a thorough knowledge of the subject. Last
year, we determined that, if possible, we would work out this
subject so far as concerned the species in our locality. For
this purpose we had made a number of mating-boxes. The
larger ones were 15 inches long by 114 wide and 3 deep; the
smaller, 74 long by 5? wide and 24 deep. The sides of each
box were marked off into inches so that the distance of the
spiders from each other could be easily noted. The floor was
made of coarse cotton cloth, for the purpose of ventilation,
while the top was of glass, so that the inmates of the cage could
be kept fully in view at all times; this top could be opened and
closed. Asa usual thing we move into the country toward the
last of June, but this year we went out on the 22d of May, in
order to be in time for those species that mature early.

The courtship of spiders is a very tedious affair, going on
hour after hour. We shall condense our descriptions as much
as possible, but it must be noted that we often worked four or
five hours a day for a week in getting a fair idea of the habits
of a single species.

SAITIS PULEX.

On reaching the country we found that the males of Saites
pulex were mature and were waiting for the females, as is the
way with both spiders and insects. In this species there is but
little difference between the sexes. On May 24th, we found a
mature female and placed her in one of the larger boxes, and
the next day we put a male in with her. He saw her as she
stood perfectly still, twelve inches away; the glance seemed to
excite him and he at once moved toward her; when some four
inches from her he stood still and then began the most re-
markable performances that an armorous male could offer to
an admiring female. She eyed him eagerly, changing her
position from time to time so that he might be always in view.
He, raising his whole body on one side by straightening out
the legs, and lowering it on the other by folding the first two
pairs of legs up and under, leaned so far over as to be in dan-
ger of losing his balance, which he only maintained by sidling

38 PECKHAM. | Vol. 1.

rapidly toward the lowered side. The palpus, too, on this side
was turned back to correspond to the direction of the legs nearest
it. (Fig. 13.) He moved in a semi-circle for about two inches
and then instantly reversed the position of the legs and circled
in the opposite direction, gradually approaching nearer and
nearer to the female. Now she dashes toward him, while he,
raising his first pair of legs, extends them upward and forward
as if to hold her off, but withal siowly retreats. Again and
again he circles from side to side, she
gazing toward him in a softer mood,
evidently admiring the grace of his
antics. This is repeated until we
have counted 111 circles made by
the ardent little male. Now he
approaches nearer and nearer and
when almost within reach whirls
madly around and around her, she
joining and whirling with him ina

Fig. 13.—-Saitis pulex. Male i ; ‘
dancing before female (from na- oiddy maze. Again he falls back and

ture, by Mr. Ludwig Kumlien).
resumes his semi-circular motions,

with his body tilted over; she, all excitement, lowers her head
and raises her body so that it 1s almost vertical; both draw nearer;
she moves slowly under him, he crawling over her head, and
the mating is accomplished.

After they have paired once, the preliminary courtship is
not so long. When this same pair mated a second time, there
were no whirling movements, nor did the female lift her body,
as at first. We watched this species a great deal during the
three weeks that the mating lasted. Once we saw a female ap-
proach a very glum-looking male, waving her palpi and making
herself agreeable, but in vain, He was pushed a little from
without, so as to make him look toward her, when she turned
about, holding her abdomen high and her head low. Finally
he grew excited enough to dance a little, and then they whirled
round and round together in the usual manner; but she
appeared the more eager of the two. ‘This was true, however,

s

No. 1.] SEXUAL SELECTION IN SPIDERS. 39

of only this one female. All the others were more retiring,
and were never more than half willing to be wooed.

The males, while very excitable in the presence of the
female, do not seem to be especially quarrelsome. When ex-
cited, they pursue and leap upon each other, but do not exactly
fight. During the display of the male before the female, she
is no inattentive observer, but watches him intently, turning
frequently to keep him in view as he dances from side to side,
and, finally, if she approves of him, yields to his desires.
Often, however, the male fails to make an impression upon her,
even after dancing before her fora long time, since upon his too
near approach, she runs away.

EPIBLEMUM SCENICUM.

On the afternoon of the 10th of June we found two males
of this species fighting on a brick wall. They held up the first
pair of legs and moved rapidly in front of each other, now
advancing and now retreating, in a half circle, distant from
each other about four and a halfinches. There was little real
earnestness in the affair, and it reminded one of the bluster of
two boys, each threatening the other and daring the other to
strike, but neither willing to be the aggressor. In a few
minutes they both wandered away. During the next two days
we found eighteen males and four females on this wall, which
was about 20x12 feet in size. The performances of the male
are not so complicated and interesting in this as in the pre-
ceding species, nor do the males seem to be so persistent.

We placed twelve spiders, of both sexes, in one of the
boxes. Soon they were all moving about, the males making
advances to the females, who seemed to endeavor to escape.
After about two hours, we found that three pairs had come to
an agreement and mated, the male, in each case, getting his
female into a corner of the box and spinning a cover over and
around her. Sometimes, while the male was working, the
female would wander off several inches, but when the house
was nearly completed, he would follow her, and half lead and
half drive her home, when he would get her into the nest first,

40 PECKHAM. [Vol. 1.

and then follow himself. Here the mating would be accom-
plished, after some slight preliminaries. The females seemed
to have some difficulty in choosing from among the males, but,
after a decision had been reached and a male accepted, there
appeared to be complete agreement, and the male, thereafter,
commenced to build his house. On the next morning we
found all the pairs together in different tents.

The male, when prancing before the female, stood quite
high on the three posterior pairs of legs; the first pair, the
palpi, and the long falces, were stretched out stiffly in an oblique
direction, the spider moving rapidly from side to side.

ICIUS SP.

This species, still undescribed, we discovered last summer,
in large numbers, on rail fences at the edge of woods. We had
worked over the place time and again, for many years past,
but had overlooked them, not only on account of their admira-
ble protective coloring, but from the fact that they only congre-
gate, in this way, until they have mated, and afterward wander
back into the woods and are then rarely met with. This is a
habit with several Attidx’ and reminds one of the “sécaleli” or
dancing-parties of certain birds, or of our own partridge dances.
We were fortunate in discovering them just at the mating
season. A dozenor more males and about half as many
females were assembled together within the length of one of
the rails. The males were rushing hither and thither, dan-
cing opposite now one female and now another; often two
males met each other, when a short passage of arms followed.
They waved their first legs, sidled back and forth, and then
rushed together and clinched, but quickly separated, neither
being hurt, only to run off in search of other and fairer foes.
We watched them for hours, and then, our patience being ex-
hausted, filled all our bottles and carried them home. We placed
them in the smaller boxes, since we have learned that pro-
pinquity is quite as effective in hastening the courtship of

1In the genus Dendryphantes, capitatus and elegans are examples. Going to
their favorite bushes we have caught 40-50 males in a few hours’ sweeping, but after
the season the same locality would not yield more than 2-3.

No. 1.] SEXUAL SELECTION IN SPIDERS. 41

these little creatures as it issaid to be among the higher races.
For several days, in visiting this fence, we found goodly num-
bers on each rail, but after a little they grew scarcer and
scarcer and at last we were unable to find one where a short
time before they had been so common.

It was much more comfortable to study them after they
had been put into the mating boxes and within the next few
days we had seen many of them pair. The males were very
quarrelsome and had frequent fights, but we never found that
they were injured. Indeed, after having watched hundreds of
seemingly terrible battles between the males of this and other
species, the conclusion has been forced upon us that they are
all sham affairs* gotten up for the purpose of displaying before
the females, who commonly stand by, interested spectators.
This is entirely contrary to what we had expected, and early in
the season we, on several occasions, forcibly parted the combat-
ants, fearing that they would kill each other. The falces in
many of the males are, it is true, much lengthened, but as
weapons of offense the shorter fangs of the female are much
more deadly. In twelve species, in which we witnessed num-
berless fights, we could never discover that one of the valiant
males was wounded in the slightest degree.

In this new species the position of the female while watch-
ing the male is unlike that of any of the others. She lies close
to the ground with her first legs
directed upward and forward,
while her second legs are held
on the ground and stretched for-
ward in front of her face (Fig.
14), The male, when approach- Fig. 14—Undescribed species. Position
nes herdoes mot tarow, Ins legs offemalewhen approhehed! by male (trom

high over his head, as he does
before another male, but raises his body on his six hind legs;

1 Cuvier remarks that “the males sometimes engage in contests in which their
manceuvres are very singular, but which do not terminate fatally.” Animal Kingdom,
trans. by Carpenter and Westwood, London, 1863. p. 464.

Hentz (NV. A. Spiders, p. 133) saw two males of Linyphia communis fighting an

42, PECKHAM. [Vol. 1.

the first legs are held down toward the ground, diverging slightly
near the head, and are bent inward at the middle so that the tips
turn toward each other and meet.
(Fig. 15.) At times he turns the apex
of hisabdomen down; at other times
he keeps it straight, as he moves from
side to side; the palpi are folded
under. He sometimes varies his atti-
tude by lying flat on his venter, keep-
ing the tips of the legs touching as

before.
HASARIUS HOYI.

; : The sexes are very different, so
Position of anale approaching fe much so that we at first described
them as two species, the male being

the more conspicuous of the two. The males are ready in the
early days of June, and the females a little later. In his dance
the male has several movements; most commonly he goes
rapidly from side toside with his first legs obliquely up; (Fig.
16); at other times he twists the
abdomen to one side and bending
low on the other, something as
pulex did, goes first in one direc-
tion for about two inches, and then,
reversing, circles to the opposite
point. The females are very sav-

of male Fanaa “Gani (ase age, especially with each other; and
ae ae even the members of the sterner
sex are not always free from danger when paying their pre-
paratory addresses. Once we saw a female eagerly watching a
prancing male and as he slowly approached her she raised her
legs as if to strike him, but he, nothing daunted by her unkindly

obstinate battle; he did not watch it to the close, but believes that it was “without
bloodshed.”

Vinson, on the contrary, mentions a fatal combat between two males of Hpeira
niger that he had shut up ina bottle witha female. Avaneides de La Reunion,
Maurices et Madagascar, p. 190. Wehaveacousin of this species, Argiope cophinaria,
and though we have seen the two or three littie males that were courting a female
manceuvre together the results were never serious.

No. 1.] SHXUAL SELECTION IN SPIDERS. 438

reception of his attentions, advanced even nearer, when she
seized him and seemed to hold him by the head for a minute—
he struggling. At last he freed himself and ran away. This
same male, after a time courted her successfully.

SYNAGELES PICATA.

These are small ant-like spiders. The most important sexual
difference, is the greater thickness of the first legs of the male.
These are flattened on the anterior surface and are of a brightly
iridescent steel-blue color. Unlike most of the Aitid males this
species keeps all his feet on the ground during his courtship:
raising himself on the tips of the posterior six he slightly
inclines his head downward by bending his front legs, their
convex surface being always turned forward. His abdomen
is lifted vertically so that it is ata right angle to the plane of the
cephalothorax. In this position he sways from side to side.
After a moment he drops the abdomen, runs a few steps nearer
the female, and then tips his body and begins to sway again.
Now he runs in one direction, now in another, pausing every
few moments to rock from side to side and to bend his brilliant
legs so that she may look full at them. We were much im-
pressed by the fact that the attitudes taken by the males served
perfectly to show off their fine points to the female. We had
never known the male of this species until the day that we
caught this one and put him into the mating-box, and it was
while studying his courtship that we noticed how he differed
from the female in his iridescent first legs. He could not have
chosen a better position than the one he took to make a display.
We had six females in the box, and saw him mate with all of
them ; and each, after a time, made a cocoon containing three
large eggs.

MARPTUSA FAMILIARIS.

This is a rather plainly marked Aftus, well protected by its
coloring of gray and black, on the bark of trees and on fences,
where it is most frequently found. There is little difference
between the sexes. We placed the two together. She saw him

44 PECKHAM. Vol. 1.

as he entered at the opposite side of the box, some thirteen
inches away. Eyeing him attentively, she slowly changed her
position to keep him in sight, and kept her palpi moving rap-
idly, a characteristic action with the species. As he neared her,
he stretched the first and second pairs of legs sideways, but, after
a moment, backed away. (Fig. 17.) These manceuvres were re-
peated many times.
Occasionally he
would bend the tip
of the abdomen
down, lifting the
= bodyup on the last

rast ie Oluts) ofmthemtwo
Fig. 17.—Marptusa familiaris. Positions in courtship;

left-hand figure female, right-hand figure male (from }jndermost le gs
nature by L. K.). :

The female always
paid the greatest attention to his movements, lying on the
ground, with all the legs flattened out and the palpi slightly
raised, the only movement visible being the vibration of the
palpi. There is a certain slowness and dignity about the
wooing of this species that is almost ludicrous.

PHIDIPPUS RUFUS.

The sexes are alike in general coloring, but the male has
much the brighter tint. In the early days of July we found
them mature and brought them together. The female standing
still, the male, while some five inches away, stood high on the
six back legs, turned the first pair forward and upward and
crossed them at the tips; the palpi were held widely apart, par-
allel with the second legs. The effect of this position was to
bring directly before her, as she stood watching him, the
beautiful white hairs on the lower part of the palpi.’ At the
same time the abdomen dropped so that it touched the ground.
In this way he advanced, with a swaying motion. The female
ran away, but after a time he renewed his attentions. The .

1, These white hairs, in contrast with the bright iridescent green falces, are
very striking; the female, although her falces are green, is without the white hairs.

No. 1.] SEXUAL SELECTION IN SPIDERS. 45

female rufus is a ferocious creature, having a great advantage
in size, and so it happened that our assiduous male, in an
unguarded moment, was pounced upon and eaten up.

PHIDIPPUS MORSITANS.

On this species we have but few notes. The single female
that we caught during the summer was a savage monster. The
two males that we provided for her had offered her only the
merest civilities, when she leaped upon them and killed them.
The sexes are quite alike in color and marking, but while the
female has the fourth leg longest, the male has the first pair
not only much the longer, but thickly adorned with white
hairs, some of which are long and others short and scale-like.
It was while one of the males was waving these handsome legs
over his head that he was seized by his mate and devoured.
The tibia of the palpus is also covered with white hairs, which
make a strong contrast with the general black color, and this is
held out in such a way as to make a display as he approaches
the female.

DENDRYPHANTES CAPITATUS.

The sexes are entirely different. In the male the bronze
brown face is made very conspicuous by some snowy white
bands, as is shown in the drawing. These are wanting in the
female, her face being rufus with some few scatterimg white
hairs. The males of capitatus are very quarrelsome, sparring
whenever they meet, chasing each other about, and sometimes
clinching. Itisa very abundant spider with us,so that we
often put eight or ten males into a box to see them fight. It
seemed cruel sport at first, but it was soon apparent that they
were very prudent little fellows, and were fully conscious that
“he who fights and runs away will live to fight another day.”
In fact, after two weeks of hard fighting we were unable to
discover one wounded warrior. ‘When the males are approach-
ing each other, they hold the first legs up ina vertical direction.
Sometimes they drop the body on to one side as they jump
about each other. These movements are very quick, and they

46 PECKHAM. [Vol. 1.

are always ready for a passage at arms. When courting the
females they have another movement. They approach her
rapidly until within two to five inches, when they stop and ex-
tend the first legs directly forward, close to the ground, the legs
being slightly curved with the
tips turned up. (Fig. 18.)
Whether it be intentional or
not, this position serves admir-
oo ifs i Denerypinte cota Te ee ite tno to the
Cee AATGEe Doe ronze and white face to the

attentive female, who watches
him closely from a little distance. (Fig. 19.) The males also
give their palpi a circular movement, much as a person does
when washing his hands. As he grows more excited, he lies
down on one side with his legs still extended.
These antics are repeated for a very long time,
often for hours, when at last the female, either
won by his beauty or worn out by his persis-
tence, accepts his addresses.

Fig. 19.—Dendry-

phantes capitatus. DENDRYPHANTES ELEGANS.

FF nd palpi of : >

male from nate, The male of the species, like many other
by L. K.).

animals, has received a number of names.
Hentz called the female elegans, and the male
superciliosus. C. Koch called him cristata, and we ourselves,
ibialis, on account of the fringe of hairs on the tibia of his
first leg. Both sexes are beautiful. The male is covered
with iridescent scales, his general color being green; in the
female the coloring is dark, but iridescent, and in certain lights
has lovely rosy tints. In the sunlight both shine with the
metallic splendor of humming-birds. The male alone has a
superciliary fringe of hairs on either side of his head, his first
legs being aiso longer and more adorned than those of his
mate. The female is much larger, and her loveliness is
accompanied by an extreme irritability of temper which the
male seems to regard as a constant menace to his safety, but
his eagerness being great, and his manners devoted and tender,

No. 1.] SEXUAL SELECTION IN SPIDERS. 47

he gradually overcomes her opposition. Her change of mood
is only brought about after much patient courting on his
part. While from three to five inches distant from her he
begins to wave his plumy first legs in a way that reminds one
of a wind-mill. She eyes him
fiercely and he keeps at a proper
distance for a long time. If he
comes close she dashes at him
and he quickly retreats. Some-
times he becomes bolder and
when within an inch, pauses,
with the first legs outstretched
before him, not raised as is com-
mon in other species ; the palpi Fig. 20.—Zygoballus bettini. Position
also are held stiffly out in front ee eae Se a ae
with the points together. Again

she drives him off, and so the play continues. Now the male
grows excited as he approaches her, and while still several
inches away whirls completely around and around; pausing, he
runs closer and begins to make his abdomen quiver as he stands
on tip-toe in front of her. Prancing from side to side, he grows
bolder and bolder, while she seems less fierce, and yielding to
the excitement lifts up her magnificently iridescent abdomen,
holding it at one time vertically and at another sideways to
him. She no longer rushes at him, but retreats a little as he
approaches. At last he comes close to her, lying flat, with his
first legs stretched out and quivering. With the tips of his
front legs he gently pats her; this seems to arouse the old
demon of resistance, and she drives him back. Again and
again he pats her with a caressing movement, gradually
creeping nearer and nearer, which she now permits without
resistance until he crawls over her head to her abdomen, far
enough to reach the epigynum with his palpus.

ZYGOBALLUS BETTINI.

The sexual differences in this species are well marked.
The male has much more silvery white on the face; the first

48 PECKHAM. [Vol. 1,

legs and falces are much longer, andon the side of the abdo-
men the general color is darker and the lateral bars of a much
more glistening white. All the colors are far more brilliant in
the malethan in the female. (Plate II.) In courting the male lies
flat near the female, wriggling his abdomen and frequently turn-
ing from side to side. His first legs are held up over his head,
slightly diverging, and are often twisted and turned about.
(Fig. 20, see p. 47.)

Two males that were displaying before one female, rushed
savagely upon each other and fought for twenty-two minutes,dur-
ing one round remaining clinched for six minutes. When
fighting, the abdomen is held nearly at a right angle with the
cep halothorax.
(Eigse 2:18) senate
combatants ap-
peared tired at the
close of the battle,
but after a short
rest were perfectly
well and fought a
number of times
subsequently.
There are two
forms of male in
this species, one
being twice as
large as the other.

Fig. 21.—Zygoballus bettini. Position of males
when fighting (from nature, by L. K.).

HABROCESTUM SPLENDENS.

The colored plate givesa good idea of the sexual difference
in this species. The male, a magnificent fellow, when we first
caught him, displayed for a long time before the female. He
began by advancing a few inches toward her and then backing
off again, this being repeated many times. After a while he
settled down under a little web in the corner. The female,
troubled by this indifferent treatment, advanced toward him ;
he came out and she fell back. This play was kept up for
some time, but at length the male began his courting in earn-

No. 1.] SEXUAL SELECTION IN SPIDERS. 49

est. When within a few inches of her he began a rapid dance
from side to side, raising the whole body high on the tips of
the legs, the first pair being directed forward and the palpi
clasped together, with the abdomen turned to one side and
lifted up. After a short dance he stood motionless, striking an
attitude, as shown in the figure, remaining quiet for half a
minute. (Fig. 22.)
Then he turned his
back on her, moving
irregularly about
with his legs forward
and his palpi vibrat-
ing. Again he dances
sideways before her,

G Fig. 22.—Habrocestum splendens. Position of
str utting and show- male approaching female (from nature, by L. K.).

ing off like a pea-

cock, or whirling around and around. When he turned his
back we often thought that the female seemed disappointed,
since she would then commonly move nearer to him and ap-
pear much excited herself. We at first supposed that this
turning around was accidental, but it happened so regularly at
a certain stage of the courtship that we concluded it was an
important part of his display, serving to better show off his
brilliant abdomen. Our artist, Mr. Kumlien, while watching
the antics in order to draw the spider, called our attention to
this habit, not knowing that we had observed it. The fact
that among spiders the males take such attitudes as display
their best points recalls this passage in one of Darwin’s letters:
“T am very glad to hear of your cases of the two sets of Hesper-
iadz, which display their wings differently, according to
which surface is colored. I cannot believe that such display is
accidental or purposeless.”

ICIUS MITRATUS.

The male is quite different from the female, especially in
his slender, tapering body and in his long first legs. While in
splendens the female was remarkable for the attention that she

50 PECKHAM. [Vol. 1,

gave the male, seeming at times to coquet with him, in this
species she was remarkable for her indifference. She takes less
interest in the display of the male than any spider that has
come under our observation. Another peculiarity of mitratus
is the large amount of time and strength given up by the
males to fighting. They do not seem so fierce as other species,
but they cannot endure each other’s proximity. A male will
leave a female in the midst of his caresses to drive off another
male that comes too near. We once sawa male jump on to the
back of another that was pairing with a female. The latter
turned on the intruder and drove him to a distance of five or
six inches, and then returned and renewed his addresses. In
courting and in fighting the position of the male is the same.
The body is somewhat raised ; the first legs are held at a right
angle to the cephalothorax, and the abdomen is twisted to one
side, and, as he dances before the female, is changed now to the
right, now to the left. (Fig.
23.) In mating, the male
does not usually crawl over
her, but jumps upon her
from a distance of one or
two inches, in this respect
agreeing with the following

species, militaris. Whether
pefore female (from nature, by Li). or no this habit in the two

species is due to the savage-
ness of the female—the females of both species sometimes
attack the males—we are unable to say.

PHILZUS MILITARIS.

This is the only species in which we saw males take pos-
session of young females and keep guard over them until they
became mature. There is a good deal of difference in the size
of the males, some being larger and some smaller than the
females. We commenced our experiments by putting half a
dozen mature males into a box. They at once began to chase
each other about and to threaten each other with upraised legs.

No. 1.] SEXUAL SELECTION IN SPIDERS. 51

The addition to the company of a number of nearly mature
females considerably increased this tendency to quarrelsome-
ness, the males thereafter spending all the time that they
spared from courtship in fighting. In approaching the female
they seemed very eager, and fairly quivered with excitement.
The first two legs were raised over the head and curved toward
each other, so that the tips nearly met and the palpi were moved
up and down. (Fig. 24.) One of them gO
was much larger than any of the others,
and from the first showed plainly that he
had a strong sense of his own superiority.
He drove all the others about at his pleas-
ure, constantly interrupting their attempts
at courtship. This big fellow seemed to
be especially attractive to the females, of
which there were always two or three
standing in an admiring circle around pig. 94 phieus mili-
him. When he approached them, however, 20 Ssachtaw female (rom
they slippedaway. After a time, he singled sagt tgs on

out the largest of the females, half coaxed and half drove her
into a corner, and there kept her secluded, chasing away every
spider that approached, irrespective of sex. He once interrupted
a courtship which was going on six inches away, driving the male
to a distance and then pursuing the female for a long time.
This seclusion of the female was kept up until evening of the
next day—a period of twenty-four hours—but on the following
morning the pair had separated and he was hidden among
some leaves. None of the females were yet mature. We now
put into the box another male, which was nearly as large as
the first. This second one adopted the same bullying manner
to the smaller members of his sex that the first had done.
After driving them about for a time, he secured a gnat, and
was peacefully devouring it, when number one emerged from
the leaves, caught sight of the new-comer, and at once
approached, bristling with pride and ire, his first legs raised
high, as if to strike, his palpi vibrating with excitement, and

52 PECKHAM. [Vol. 1.

his abdomen dragging, first on one side and then on the other.
Number two was evidently of good courage, for he held his
ground, and, not relinquishing the gnat, raised his legs and
clinched with hisantagonist. The battle raged for five minutes ;
finally number one pulled the gnat from the other, and then
chased him away.

For several days following life in the mating box was
robbed of its monotony by perpetual battles among the males.
The females, in eluding them, jamped and hung from a
thread. At one time a small one guarded a female for some
hours in a corner; she once slipped away and ran a few inches,
but when another male began to pay court to her, she ran back
and crept under the body of her protector. After two or three
days each of the two large males took possession of a female,
spun a web over hex, and spinning a second sheet above as a
cover for himself, remained quiet in the little nest thus formed
fora week. During this time every spider that approached
was driven away. They went out occasionally for food, but
were not seen to carry any to their mates.

At the end of a week number one was observed to be
pairing with his female, which had moulted and was now
mature. The two were separated, when the male went hunt-
ing about and finally sprang upon an unmated female, three
inches away from the other nest, whereupon number two ran
out, attacked him violently, drove him away, and then returned
to his nest. Number one, while wandering about, caught sight
of his own mate and sprung upon her without any of the
preliminary attention before noticed. From this time forward,
the big, wandering male, his occupation gone, became a very
thorn in the flesh to the other, whose female had not yet
matured. Not only did he continually approach the nest, thus
arousing a jealous fury in its owner, which was not called out
by any of the other spiders, but whenever the rightful owner
was away from home, chasing intruders or procuring food, this
disturber of domestic peace made his way into the nest. The
first time this happened, the owner, returning, ejected him

No. 1.] SEXUAL SELECTION IN SPIDERS. 53

without ceremony; the second time they had a prolonged
struggle, clinching, and falling, thus locked together, a distance
of about twelve inches—the height of the box (Fig. 25); the
third time number one
was not discovered until
he had cut the still im-
mature female out of the
web which enclosed her.
She ran away, and after
that the two males wan- =
dered about, fighting
whenever they met. The

Fig. 25.—Phileus militaris. Position of males
defrauded male, as wel] when fighting (from nature, by L. K.).

a
as the other one, now

courted every female in the box, although so long as they had
their own mates they had paid no attention to other females,
except to drive them away.

The following extract from our notes shows that the guard-
ing of young females is a habitof the males in this species, and
was not the result of artificial conditions:

“Aug. 17. Found a mature male militaris standing guard,
in a tent, over an immature female (one moult from maturity).
They seemed very friendly when taken out and put into a bottle.
The webs and positions were as we had seen them in our
mating-boxes.

ASTIA VITTATA.

There is a good deal of interest connected with the study
of this species, for the reason that there are two well marked
male forms; moreover, their love antics are unusually curious.
A description of the two males is unnecessary, since they are
well represented on Plate II. The two forms grade into each
other, excepting that the three hair tufts are only found in the
fully developed niger form. The vittata form, which is quite
like the female, when he approaches her, raises his first legs
either so that they point forward or upward, keeping his palpi
stiffly outstretched, while the tip of his abdomen is bent to the

54 PECKHAM. [Vol. 1,

ground. ‘This position he commonly takes when three or four
inches away. While he retains this attitude he keeps curving
and waving his legs in a very curious manner. Frequently he
raises only one of the legs of the first pair, running all the time
from side to side. As he draws nearer to the female he lowers
his body to the ground, and, dropping his legs also, places the
two anterior pairs so that the tips touch in front, the proximal
joints being turned almost at
a right angle to the body.
(Fig. 26.) Now he glides in a
semi-circle before the female,
sometimes advancing, some-
times receding, until at last
she accepts his addresses. The
niger form, evidently a later
development, is much the
more lively of the two, and

whenever the two varieties

Fig. 26.—Astia vittata. Position of male

approaching female (from! mature, by were Seen! LO compete for a fe-

male, the black one was suc-
cessful. He is bolder in his manners, and we have never seen
him assume the prone position, as the red form did, when close
to the female. He always held one or both of the first legs
high in the air, waving them wildly to and fro, or, when the
female became excited, he stood perfectly motionless before her,
sometimes for a whole minute, seeming to fascinate her by the
power of his glance. (Fig. 27, see p. 55.) A female that was
full of eggs was looked at critically from a distance of four or
five inches by several ardent males, but received no further
attention. Although the males were continually waving their
first legs at each other, their quarrels were harmless. It was
quite otherwise with the females, since they not only kept the
other sex in awe of them, but not infrequently, in their battles,
killed each other. We thought it rather remarkable that the
niger variety should not have the same antics as the vittata ;
but since closely related species often differ greatly in color, form

No. 1.] SEXUAL SELECTION IN SPIDERS. 55

and habits, we should not be surprised at finding like differ-
ences between distinct varieties.

The very meager knowledge that we have of the mating
habits of the Hpeiride has been gained at the expense of num-
erous hours of watching. The courtship of Attidx is often very
tedious, but it does not compare in this respect with that of the
peiride, perhaps because the members of the former family
are constantly in motion and thus hold out a hope to the ob-
server that he is going to see something worth seeing, while
the orb-weavers make nothing of remaining motionless for six
or eight hours at a stretch; the observer, in the meantime, be-
ing afraid to let his attention flag
for a moment lest he lose some
small but significant movement
on their part. We have watched
the males and females of several
species, but our only notes per-
tain to two species of Argiope,
cophinaria and fasciata, in which
the males are much smaller than
the females. In the mating sea-
son each female has three or four Fig. 97.—Astia vittata, var. niger.
of these little males hanging Guam sodene te approgeline poy
about the outskirts of her web.

In cophinaria, when two of these males meet, they throw
up their first legs and back away from each other, without
striking or clinching as in the Aftidx, and then one of them
drops at the end of a line. When advancing toward the
female, the male seems to pause and pullat the strands of web,
as though to notify her of his approach. When he comes
toward her from in front she imparts a slight motion to the
web with her legs, which seems to serve as a warning, as he
either moves away or drops out of the web. When he comes
from behind she pays no attention to him until he begins to
creep on to her body, when she slowly raises one of her long
legs and unceremoniously brushes him off.

56 PECKHAM. [Vol. 1.

We passed one afternoon in watching a female of fasciata in
her web, around the edge of which were perched four little
males. The proceedings were briefly as follows:

One of the males ran lightly over the web toward the
female, approaching her from behind. Before he reached her
she, seemingly conscious of his approach, gave the web a violent
shake, whereupon he retreated. He made three or four trials
of this kind and then seemed to give up hope. His place was
taken by one of the other males, which acted in exactly the
same way, with no greater success, and then gave place to a
third. ‘The female was always approached from above and be-
hind, she hanging head downward, and she usually gave her
warning shake before the male came very near, although once
or twice he came close enough to touch her. The males
showed no ill feeling toward each other. The most interesting
part of it was that she seemed to recognize from the character
of the vibration that a male was approaching, not taking the
motion of the web to signify that an insect was entangled in
it, as in this case she would at once have turned to secure her
prey.

From these slight observations we were inclined to believe
that the courtship in the Epetride was carried on, to some extent
at least, by a vibration of web lines. Dr. McCook subsequently
confirmed that opinion, and we quote from his work on Ameri-
can Spiders and their Spinning Industry the following extract,
which bears directly on the subject :

“The first stages of courtship have already been indicated.
Having found the snare of his partner, the male stations him-
self upon the outer border and awaits results. It is not difficult
for him to communicate his presence. Indeed, he must take his
place deftly and keep it very quietly upon the snare, or he will
quickly bring down upon him the voracious lady of the house.
A touch of his claw upon a radius would telegraph to the
female the fact of his presence; and I believe, from what I have
seen of the operations of the male in this preliminary stage of
courtship, as well as from the recorded observations of others,

No. 1.] SEXUAL SELECTION IN SPIDERS. 57

that he does thus intimate his presence, and that the first stages
of the engagement are consummated by these telegraphic com-
munications back and forth between male and female over the
delicate filaments of the silken snare.

“If matters be favorable, the male draws nearer, usually by
short approaches, renewing the signals at the halting places.
Sometimes this preliminary stay is very brief; sometimes it is
zreatly prolonged. I have observed it to be continued during
several days, in which the male would patiently wait, some-
times, but not always, changing his position until his advances
were favorably received, or were so decidedly repulsed that he
was compelled to retire. With Labyrinth spiders I have gener-
ally seen the male stationed upon the maze, or that part of the
snare which consists of crossed lines. Here he would make for
himself, as he hung back downward, a little dome of spinning
work, which spread above him like a miniature umbrella. The
male of Argiope cophinaria feels the web with his feet for some
time before the final approach. The male of Linyphia margi-
nata, as he cautiously approaches, pulls upon the threads con-
necting his own with his lady’s bower. The period of ap-
proach or courtship is generally terminated by a sudden rush
which brings the partners into union.”

The same idea was advocated many years ago by Termeyer,
as follows: *

“The diadema spider was that which I examined. * * *
He never appears in the center of the beautiful webs, and even
when I saw him he was, as to abdomen and palpi, so different
from the female, which in other respects he resembled, that I
should not have supposed him of the same species. He never
spins webs except in the time of his amours. * * * He
approaches ltttle by little, with much caution, doubtful of the re-
ception with which he is to meet in the web of the female, who
occupies the center, intent only on her prey. He commences

1 Researches and Experiments upon the Silk from Spiders and upon their
Reproduction. Raymond Maria de Termeyer. Revised by Burt G. Wilder, M.D.
Proceedings of Essex Institute, Vol. V, pp. 71-73.

58 PECKHAM. [Vol. 1.

by touching with one leg a thread of her web; the female
approaches him ; he flies, allowing himself to hang. Then he
rises, winding up the thread, when he is assured, by I know not
what movement, that he will not be ill-received; then he
approaches her and with one of the palpi touches her stomach
quickly many times. Then he returns, repeats the same act and
departs, if he succeeds in leaving. I say if he succeeds, because
I wish to relate what came under my observation in 1798. * * *
I put a male and female of the diadema spider together in a box
like a drum, closed with a veil at both ends. The male began
by making various movements, as if to draw the attention of
the female, who pretended not to perceive him, but only from
time to time touched some thread of the web. He boldly
approached, directing one of his palpi to her abdomen, and she
extending this toward the palp. * * * But I saw also with
surprise and indignation that, the work hardly finished, the male
not being able to fly on account of the confinement, the female
enveloped him in her thread, and having thus deprived him of
every means of defense, devoured him. Perhaps overpowering
hunger compelled her.to it, but the act was very ferocious.”

SUMMARY AND CONCLUSION.

In this paper we have considered the two theories by which
Mr. Wallace explains sexual color differences in animals—pri-
marily the greater vitality of the males, especially during the
breeding season, and secondarily the greater need of protective
coloring on the part of the females; and we have found that
however satisfactory they may ke where birds and butterflies
are concerned, they fail in each important particular when
applied to spiders.

In our study of moulting habits we have seen that among
the Attidx, where the sexual differences are strongest, males are
commonly more brilliant than the females; that the young
males nearly always resemble the adult females; that the males,
when they differ from the females, depart from the general
coloring of the group; and that when the females depart from
the coloring of the group they approach, in the same degree,

No. 1.] SEXUAL SELECTION IN SPIDERS. 59

the coloring of the males. Mr. Wallace’s theory would only
partially explain these facts since although the increased vital-
ity at the breeding season might produce variations which
would tend to be inherited at that age, the assumption with
which he starts out—that the male animal is constitutionally
more active than the female—is not true in regard to spiders.

While studying the secondary sexual characteristics of
spiders we came upon several large groups of facts which seem
entirely inconsistent with Mr. Wallace’s view. First, we found
no evidence that the male spiders possess greater vital activity ;
on the contrary, it is the female that is the more active and
pugnacious of the two. Second, we found no relation, in either
sex, between development of color and activity; the Lycoside,
which are among the most active of all spiders, having the
least color development, while the sedentary orb-weavers show
the most brilliant hues. Third, we found that in the numerous
cases where the male differed from the female by brighter colors
and ornamental appendages, these adornments were not only
so placed as to be in full view of the female during courtship,
but that the attitudes and antics of the male spider at that time
were actually such as to display them to the fullest extent
possible. Moreover, we noticed that the males were much more
quarrelsome in the presence of the females, and that they, toa
great extent, lost their tendency to fight when the mating
season was Over.

With these facts in mind let us examine Mr. Wallace’s two
strongest objections to the theory of sexual selection.

First: “There is a total absence of any evidence that the
females admire or even notice the display of the males.
Among butterflies there is literally not one particle of evidence
that the female is influenced by color or even that she has any
power of choice, while there is much direct evidence to the con-
trary.’ In butterflies and in birds, with their rapid flight, it is
difficult to determine how much one sex is watched by the
other; but in the Attide we have conclusive evidence that the

1 Tropical Natwre, pp. 199-200,

60 PECKHAM. [Vol. 1.

females pay close attention to the love dances of the males, and
also that they have not only the power, but the will, to exercise
a choice among the suitors for their favor..

Second: The fact that every male bird finds a mate
“would almost or quite neutralize any effect of sexual selection
of color or ornament; since the less highly colored birds would
be at no disadvantage as regards leaving healthy offspring.”
In spiders, as the females gradually become adult, they have a
choice from among a number of males, asthese mature several
days earlier. The males will pair as often as they have the
opportunity and as the mating season lasts for two or three weeks
the more brilliant males may easily be selected again and again.

The fact that in the Atlide the males vie with each other
in making an elaborate display, not only of their grace and
agility but also of their beauty, before the females, and that the
females, after attentively watching the dances and tournaments
which have been executed for their gratification, select for their
mates the males that they find most pleasing, points strongly to
the conclusion that the great differences in color and in orna-
ment between the males and females of these spiders are the
result of sexual selection.

Nore.—Since finishing the above we have seen, in the February
number of the Popular Science Monthly, T. H. Morgan’s article on
The Dance of the Lady Crab. The observation therein noted is full of
interest, showing, as it does, that sexual display in the invertebrates is
not confined to spiders.

PROTECTIVE RESEMBLANCES IN SPIDERS.

ELIZABETH G. PECKHAM.
Introduction.

There are, among spiders, two forms of protective modifi-
cation: the first, including all cases of protective resemblance
to vegetable and inorganic things—that is, all modifications of
color or of color and form that tend to make them inconspicu-
ous in their natural relations—I shall call direct protection.
The second form, which I shall call indirect protection, includes
two classes, the spiders which are specially protected themselves
and those which mimic other creatures which are specially
protected.*

Spiders are specially protected when they become inedible
through the acquisition of hard plates and sharp spines. The
modification of form is frequently accompanied by conspicuous
colors, which warn their enemies that they belong to an unpal-
atable class. }

The second class of indirectly protected spiders—those
that mimic specially protected creatures—presents some difficul-
ties, since it is not always easy to determine whether the pur-
pose of mimicry is protection or the capture of prey. The
resemblance may, as is frequently the case in direct protection,
serve both purposes.

In looking for instances of protective form and color
among spiders we encounter one difficulty at the outset. The

* Wallace classifies the colors of animal organisms as follows:
Protective colors.

(a. Of creatures specially protected.
Warning colors. { b. Of defenseless creatures mimicking a.
Sexual colors.
Typical colors.

Tropical Nature and Other Essays, p. 172..

Pe we

+ Under special protection would also fall cases, suchas are common among other
animals, of the development of some nauseous taste or odor; but we know of no such
case among spiders.

62 PECKHAM. [Vol. 1.

meaning of a protective peculiarity can be determined only
when the animal is seen in its natural home. The number of
strangely modified forms depicted in descriptive works on
spiders is enormous. Bodies are twisted, elongated, inflated,
flattened, truncated, covered with tubercles or spines, enclosed
within chitinous plates, colored like bark, like lichens, like
flowers of every imaginable hue, like bird droppings, like sand
or stones, and in every one of these modifications there is doubt-
less an adaptation of the spider to its surroundings which,
when it is studied out of its natural relations, we can only
guess at.

It has been well said that in these protective resemblances
those features of the portrait are most attended to by nature
which produce the most effective deception when seen in
nature; the faithfulness of the resemblance being much less
striking when seen in the cabinet.*

Before entering upon a consideration of protective modifi-
cations, I wish to give some account of the enemies of spiders
and also to call attention to the remarkable variations in the
fertility of the different species.

ENEMIES OF SPIDERS.

The enemies of spiders are numerous and vary greatly in
different countries. Among them we may enumerate birds,
wasps, lizards, snakes, monkeys, ichneumons, some kinds of
ants, and spiders. They are also eaten in inconsiderable num-
bers by beetles and by fishes.

Outside of the Trochilidee comparatively few of the North
American birds feed to any extent upon spiders, although they
form an insignificant part of the food supply of many species.

*H, W. Bates, in Lepidoptera of the Amazon Valley, p. 507.

'Prof. F. H. King has examined the stomachs of 1608 Wisconsin birds, including
tive humming-birds, 34 families being represented, In thesehe found, among other
things, 1779 Hymenoptera, 1262 Coleoptera and 52 spiders. The whole number of birds
eating Hymenoptera was 189, the whole number eating Coleoptera 430 and the whole
number eating spiders 35.

Prof. S. A. Forbes finds that spiders appear to the following extent in the food
of Illinois birds: Robin, 1%; Catbird, 2%; Brown Thrush, 1%; other Thrushes, 1%;

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 63

The humming-birds feed largely on our small spiders.
Mr. Gentry tells me that he has opened hundreds of stomachs
of the Rubythroat (Troch. colubris), subjecting them to micro-
scopical examination, and has always found an abundance of
small spiders associated with Coleoptera and Aphide, the spiders
being ten times more numerous than the other insects. This
agrees with the statement of Mr. Belt that he has found the
crops of humming-birds full of small, soft-bodied spiders.*

In Central and South America the destruction of spiders
from this source must be enormous, since in those countries the
humming-birds are exceedingly numerous. Mr. Belt estimates
that they are so plentiful in some parts of Nicaragua as to equal,
if not to greatly exceed, all the other birds together.t+

In both temperate and tropical regions a dreaded foe of
spiders is the solitary wasp. ‘This strange creature stings and
lays up as food for its larvee great stores of spiders, or in some
species, beetles, flies, or caterpillars.

Reports from many parts of the world show how universal
is the enmity between spiders and wasps. Fabre, in speaking
of some European species of Pompilidee and of the spiders with
which they do battle, says: “D’une part sont les Pompiles,

Bluebird. 8%; House-wren. 6%; Chestnut-sided Warbler, 6%; Summer Yellow-bird,
6%; Yellow-winged sparrow, 30%.

Mr. Thomas Gentry has, with a kindness which I gratefully acknowledge, made
out for me the percentage of spiders in the food of the land birds of Eastern Pennsyl-
vania. It will be seen that his results agree with those of King and Forbes in show-
ing that the Arachnidafurnish but an insignificant part of the food of North American
birds, always excepting the Trochilide.

The Turdid@, consume a few spiders, but the ratio to the whole number of
insects eaten is so small as to be of little value.

Saxicolide, about 2%; Sylviidz, less than 4%; Paride, less than 14%; Sittide
1%; Certhiide, %%; Troglodytide, 2%; Sylvicolide, 2%; Tanagride, 34%; Hirundi-
nid, 1%; Ampelidx, none; Vireonidx, 2%: Laniidx, none; Fringillidx, repre-
sented by 28 species, .0134%; C. passerinws consumes about 32%; P. gramineus, often
as much as 10%.

Icteridx, represented by eight species, are occasional spider eaters, especially
the sub-family Icterine. Corvide, none; Tyrannide, 34%; Caprimulgide, occasional
traces of spiders: Cyprelidz, very few; Trochilidz, 80%; Alcedinide none; Cu-
culide, a few traces; Picidx, 146%; Strigidx, none; Falconidx, none; Cathartide,
none; Columbidz, none; Tetraonidz, none.

* The Naturalist in Nicaragua, p. 315.

| Loe. cit., p. 140.

64 PECKHAM. [Vol. 1.

champions toujours vainqueurs; d’autre part sont les Araignées,
champions toujours vaincus.”*

Wallace also has a reference to this family: “The Pompi-
lidee comprise an immense number of large and handsome
insects, with rich blue-back bodies and wings, and exceedingly
long legs. They may often be seen in the forests dragging
along large spiders, beetles, or other insects they have captured.
Some of the smaller species enter houses and build earthen cells,
which they store with small, green spiders, rendered torpid by
stinging, to feed the larvee.”+

In The Naturalist in Nicaragua we find the following
remarks on the relations between spiders and wasps: “The
tramway in some parts was on raised ground, in others exca-
vated in the bank side. In the cuttings the nearly perpen-
dicular clay slopes were frequented by many kinds of wasps
that excavated round holes of the diameter of their own bodies,
and stored them with sting-paralyzed spiders, grasshoppers, or
horse-flies. Amongst these they lay their eggs, and the white
grubs that issue therefrom feed on the poor prisoners. I one
day saw a small, black and yellow-banded wasp (Pompilus
polistoides) hunting for spiders; it approached a web where a
spider was stationed in the center, made a dart towards it—
apparently a feint to frighten the spider out of its web; at any
rate, it had that effect, for it fell to the ground and was immedi-
ately seized by the wasp, who stung it, then ran quickly back-
wards, dragging the spider after it, up a branch reaching to the
ground, until it got high enough, when it flew heavily off with
it. It was so small, and the spider was so heavy, that it prob-
ably could not have raised it from the ground by flight. All
over the world there are wasps that store their nests with the
bodies of spiders for their young to feed on. In Australia, I
often witnessed a wasp combating with a large, flat spider that
is found on the bark of trees. It would fall to the ground, and
lie on its back, so as to be able to grapple with its opponent;

* Les Pompiles, Nouveaux Souvenirs Entomologiques, p. 206.

+ Loe. cit., p- 90.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 65

but the wasp was always the victor in the encounters I saw,
although it was not always allowed to carry its prey off in
peace. One day, sitting on the sandbanks on the coast of
Hobson’s Bay, I saw one dragging along a large spider.
Three or four inches above it hovered two minute flies, keep-
ing a little behind, and advancing with it. The wasp seemed
much disturbed by the presence of the tiny flies, and thrice
left its prey to fly up toward them, but they darted away
immediately. As soon as the wasp returned to the spider,
there they were hovering over and following it again. At last,
unable to drive away its small tormentors, the wasp reached its
burrow and took down the spider, and the two flies stationed
themselves one on each side the entrance, and would, doubtless,
when the wasp went away to seek another victim, descend and
lay their own eggs in the nest.” *

Mr. Bates, speaking of a wasp of the genus Pelopatus, says:
“On opening closed nests of this species, which are common in
the neighborbood of Mahica, I always found them to be stocked
with small spiders of the genus Gasteracantha, in the usual half-
dead state to which the mother wasps reduce the insects which
are to serve as food for their progeny.” +

This isa particularly interesting fact since the Gasteracanthi-
des belong to specially protected group, being so armed with
spines that birds cannot eat them. Mr. Bates also mentions
two species of Trypoxylon which provision their nests with
spiders.

Monteiro, writing on the natural history of Angola, says:

“Whilst at Bembe, I fortunately witnessed a fight between a
large specimen of these wasps (Pelopzeus) and a powerful spider
which had built its fine web on my office wall. The spider
nearly had the wasp enveloped in its web several times, and by
means of its long legs prevented the wasp from reaching its
body with its sting, but at last, after a few minutes of hard
fighting, the wasp managed to stab the spider right in the

*P, 133.
+ Naturalist on the River Amazon, p. 186.

66 PECKHAM. [Vol. 1.

abdomen, when it instantly curled up its legs and dropped like
dead to the ground. * * * TI have counted as many as
twenty spiders in a single cell, and there are seldom less than
three cells together, and sometimes as many as eight or ten.” *

On the wasps of South America, in their relation to spiders,
I will also quote from a letter written by Mr. Herbert Smith +
in answer to some questions about the enemies of spiders.

“Tn my opinion, the chief enemies of spiders in the tropics
are Hymenoptera. ‘The solitary wasps are far more numerous
than here; some of the larger Pompilide provision their nests
with Mygale, but commonly take great numbers of small
Epeiridee, Attidee, ete. Some of my best specimens of spiders
were obtained from wasps’ nests, though the wasps have an
unpleasant habit of cutting off all the spiders’ legs.”

To come nearer home, Hentz, in the United States, found
about forty spiders in one tube of Sphex cyanea.{ He says
that these wasps commonly enclose from twenty to forty spiders
in their nests. §

Mrs. Treat has also noticed that wasps make war upon a
large spider, T. tigrina, which lives in a hole which it excavates
in the ground. She had at one time twenty-eight spiders of
this species under observation. She writes: “In August the
digger-wasp is making sad havoc among these spiders. She
wants them to feed her young, and nothing but this particular
species will do; and woe now to all spiders with unclosed doors,
for she is sure to findthem. * * * She runs over the ground
swiftly, peering here and there, until she alights upon an open
burrow, down which she speedily goes, and soon comes out
dragging her victim, which she has paralyzed with her power-
ful sting. * * ‘Toward the end of August out of the twenty-
eight spiders only five are left.”||

* Angola and the River Congo, p. 324.

+ Author of Brazil, the Amazons and the Coast.
t Spiders of the United States, p. 122.

§ [bid, p. 154.

|| Home Studies in Nature, p. 82.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 67

The wasps that were watched by Fabre, dared not enter
the nests of the spiders they wished to capture, only attacking
them when they came partly outside.

Lastly, we ourselves have opened a number of Sphex nests,
which we always found to contain twenty-five or thirty spiders,
nearly all of them being E. strix.

In regard to the other enemies of spiders, I will quote again
from Mr. Smith’s letter:

“The smaller monkeys, I know, prey upon spiders a good
deal; they seem to delight in tearing them to pieces even when
they do not eat them. I have observed this frequently with
small Cibi and marmosets. To these mammalia I should add
some kinds of armadilloes and all the ant-eaters; the latter
devour ‘white ants’ by preference, but I have generally found
their stomachs filled with all sorts of insects, wasps, beetles, etc.,
and (if | remember rightly) terrestrial spiders. Snakes eat
spiders sometimes, as I can attest from actual observation ; no
doubt lizards do the same. Owls may sometimes eat the larger
nocturnal species, and I feel pretty sure that I have seen other
birds eating them. Foraging ants (eiton) kill great numbers
of terrestrial spiders and some arboreal ones, though the latter
generally escape them by letting themselves down on lines.
Scorpions do not eat spiders I think; at all events the latter do
not seem at all afraid of them. Except the foraging ants, I
never saw ants attack living spiders; the butchery is all on the
other side. As you observe, the spiders eat each other; yet I
should not think that the destruction from this cause was very
great. Spiders as well as insects are sometimes killed by para-
sitic fungi.”

My own observations have led me to think that hunting
and running spiders prey to a considerable extent upon each
other. We have had great difficulty in keeping numbers of
Attidee, even of one species, together in our boxes, since, although
they were supplied with gnats and flies, they preferred to
devour each other. Phid. morsitans, Phid. rufus, Hasarius hoyt,
Astia vittata and Phil. militaris were especially troublesome in

68 PECKHAM. [Vol. 1.

this respect. A large Lycosa, which we kept under observation
for some time, instantly seized and devoured any smaller spider
that was put into the box with it. The Thomiside are very
fierce and voracious, attacking and eating Attidee larger than
themselves when caught with them in a sweep-net—a time at
which all other captured creatures think only of how to escape.

Walckenaer refers again and again to the warfare going on
among spiders. In his introduction, after giving some account
of the conflicts between males and females of the same species,
he goes on to say:

“Tf individuals of the same species behave toward each
other with such ferocity, one may well believe that different
species and different genera are in a state of continual war.” *

Spiders of one genus, Mimetus, have developed a habit of
taking possession of the webs of other spiders, first devouring
the owners and sometimes their eggs as well.+

We have other instances of spider eggs being eaten by
spiders. For example, Vinson gives a graphic description of
the great Epeiride of Madagascar, in the corners of whose
mighty webs live many small Argyrodes, which thus secure
immunity from the attacks of birds. These little spiders,
unmolested by their big relatives, sometimes make a poor return
for the hospitality shown them by devouring the eggs of their
hosts. {

Many spiders are destroyed by parasites whose eggs may
be deposited upon, or within the body of the spider, or may be
laid within the cocoon, the parasitic larvee devouring the eggs.
It is a very common thing to find spider cocoons inhabited by

* Hist. des Insectes Apteres, I, p. 148. See alsopp. 172,, 408., 644, and vol. II, pp.
ay) "Al,

+ In characterizing this genus Hentz says: “The parasitic habits of the spiders
composing this sub-genus, remind the naturalist of the depredations committed by
various Hymenoptera upon many species of insects. The Mimetus can make a web
like that of Theridion, but prefers prowling in the dark, and taking possession of the
industrious Epeiras’ threads and home, or the patient Thendion’s web, after murder-
ing the unsuspecting proprietor.” Loc. cit., p. 187.

t Araneides des iles de La Reunion, Maurice et Madagascar, p. 269.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 69

young ichneumons; and it is probable that spiders have no
more destructive enemies than these insects.

FERTILITY OF SPIDERS.

As we have for some years made a practice of keeping
notes on all observations relating to spiders, whether they
touched on work on hand at the time or not, it happened that
we found ourselves, some time ago, in possession of a good
many facts concerning the number of eggs laid by different
species. These numbers varied so greatly, running from forty
or fifty up to several hundred, as to excite considerable specu-
lation, on our part, asto the meaning of the variation.

Why should one species lay eight hundred or a thousand
eggs, while another, equally common, laid only fifty ?

At about this time we had, in confinement, one male and
half a dozen females of the little ant-like spider, Synageles picata,
and before long each female made a cocoon containing three
eggs. This number was so small as to still further arouse our
interest and the idea suggested itself that a possible explanation
might be found in the principles laid down by Herbert Spen-
cer in regard to the inverse variation, in every species, of its
birth rate to the powers of self-maintenance possessed by its
individual members; and that if this could be established it
would have a direct bearing on protective resemblances, since
one test of the advantage of its own peculiar modification to a
species might then be found in the number of eggs laid by
that species.

To show how this doctrine bears upon the subject I will
briefly state Spencer’s introductory considerations, and will
then quote at length from that part of his discussion which
applies to the point in question.

The varying degrees of fertility among organisms result
from their conditions of life. We may class the actions which
affect each race of organisms as forming two conflicting sets.
On the one hand, by what we call natural death, by enemies,
by lack of food, by atmospheric changes, etc., the race is con-
stantly being destroyed. “On the other kand, (a) partly by the

70 PECKHAM. Vol. 1.

endurance, the strength, the swiftness, and (b) partly by their
fertility, it is constantly being maintained. These conflicting
sets of actions may be generalized as the forces destructive of
race and the forces preservative of race.”

There exists an equilibrium between the destructive and
preservative forces of every species. Any excess of either of
these sets of forces itself generates, by the deviation it pro-
duces, certain counter-forces that eventually out-balance it and
initiate an opposite deviation.

“Ts this the sole equilibration that must exist? Clearly
not. The temporary compensating adjustments of multipli-
cation to mortality in each species are but introductory to the
permanent compensating adjustments of multiplication to
mortality among species in general. The above reasoning
would hold just as it now does, were all species equally prolific
and all equally short-lived. It yields no answer to the
inquiries—why do their fertilities differ so enormously, or why
do their mortalities differ so enormously? And how is the
general fertility adapted to the general mortality in each?
The balancing process we have contemplated, can go on only
within moderate limits—must fail entirely inthe absence of a
due proportion between the ordinary birth-rate and the
ordinary death-rate; * * * the minor adjustment of vary-
ing multiplication to varying mortality in each species, implies
some major adjustment of average multiplication to average
mortality. What must this adjustment be?

“We have already seen that the forces preservative of race
are two—ability in each member of the race to preserve itself,
and ability to produce other members—power to maintain
individual life, and power to generate the species. These must
vary inversely. When, from lowness of organization, the
ability to contend with external dangers is small, there must be
great fertility to compensate for the consequent mortality;
otherwise the race must die out. When, on the contrary, high
endowments give much capacity of self-preservation, a
correspondingly low degree of fertility is requisite. Given the

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 71

dangers to be met as a constant quantity; then, as the ability
of any species to meet them must be a constant quantity too,
and as this is made up of the two factors—power to maintain
individual life and power to multiply—these cannot do other
than vary inversely: one must decrease as the other increases.”*

To make a fair application of this to spiders—to determine
with any degree of certainty whether the spiders that lay a
large number of eggs are poorly equipped for individual main-
tenance, while those that lay a small number are well equipped,
we ought to have many more facts than are at present ayaila-
ble about the conditions of life in the different species. It is
interesting, however, to see how what facts we hayveaccord with
the theory, and, supposing the theory to be correct, to see which
forms of protection are most successful.

To take two species from the same family, we have no
other Hpeirid which lays so many eggs (500—-2,200) as Argiope
cophinariat and no other which lays so few (34) as Tetragnatha
laboriosa. According to the theory, cophinaria should be ill equip-
ped for the battle of life while laboriosa should be in much closer
harmony with its relations.

Both depend upon their webs for their food supply and
probably both secure as much as they need, so that their
advantages in this respect may be considered equal.{

In regard to their means of protection from enemies, a
first view of the two spiders would seem to favor our theory.
The slender, elongated form, the greenish-golden color, blend-
ing with that of the leaves, the habit of clinging, with legs
extended ina line with the body, close to the branch upon
which it rests, all combine to render laboriosa inconspicuous.
On the other hand, we have in the great cophinaria, dressed

* Principles of Biology, Vol. Il, p. 396, et seq.
+A. riparia Hentz.

} The zig-zag band of white silk which runs up and down through the middle of
the cophinaria web is used in the capture of prey by a relation of our spider in Mada-
gascar. Itservesasareserve line with which to tieup any extraordinarily large
insect, such as a grasshopper, when he becomes entangled in the web. Cophinaria,
however, is not known tomake this use of it, its only usefulness to her being the added
strength which it givesto the web. Vinson, loc. cit., p. XV.

72 PECKHAM. [Vol. 1,

in deep black and brilliant yellow, hanging out in the middle
of her web, so striking an object that every passer-by must see
her. An old-fasioned naturalist might be pardoned for calling
her a wonderful instance of an all-regulating Providence,
which has not only provided this lucious morsel to be the food
of some bird, but has also made her so conspicuous that the
bird cannot fail to see and recognize its natural prey. *
Cophinaria, however, is not unprotected. Of one means
of defense common among conspicuous creatures, 7. ¢., the
possession of a nauseous flavor, she seems to be destitute, as
some chickens, to which she was offered, ate her with relish;
but her size alone must protect her from a host of enemies
that prey upon smaller
species. For creatures
large or fierce enough to
attack her we must look
to birdsand wasps. From
these foes she is protected
by a number of irregular
lines which she stretches
beyond her web (fig. 1).
These must be passed be-
fore the spider can be
reached. Now cophinaria
has a delicate sense of
touch. Place your finger
lightly upon one of the
outlying lines—she falls
like a shot to the ground,
Fig. 1.—Web of Argiope cophinaria, showing Where,with her back down,
outlying lines (from McCook). é
and her legs drawn in she
is difficult to find, unless you have followed the drop with your
eye. Or approach the web without touching it; your shadow,
the sound of your footstep, or perhaps the vibration of the

A
ie

* Darwin (Descent of Man, p. 348) says that M’Clelland, in describing certain
Indian Cyprinidae, supposes that their remarkable brilliancy serves as a better mark
for the birds which are destined to keep the numbers of these fishes in check.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 73

ground warns her; still, the danger does not seem imminent;
she has time to make use of another power—she will render
herself invisible. The web begins to sway backward and _ for-
ward; the rapidity of the motion increases; the outlines
become indistinct, and within a few seconds of the first
movement, spider, web and all have vanished from sight!

If a wasp, in attacking cophinaria, becomes in the least
entangled in the web the position is quickly reversed. The spider
darts to the spot, holds the would-be destroyer, who is now the
victim, away from her body with her long legs, while she
rapidly binds it up and reduces it to a condition of perfect
helplessness. *

The young cophinaria is more open to attack than the
adult, but is by no means so conspicuous. It is of a light,
somewhat greenish tint, so intermingled with dark gray as to
give the effect of transverse dark bands on a light ground.
The legs are also light, banded with a darker shade. The web
made by the young spider differs from that of the adult and is
curiously adapted to conceal it, having a thickened place in the
middle, which extends as far as the tips of the spider’s legs
This thickened portion is made up of concentric lines of web
joined by short, transverse threads, so that it blends with the
banded body and legs of the spider and protects it from
observation.

Cophinaria, then, is so protected, at different periods of its
life, that the disadvantage of its conspicuousness is, to some
extent, counterbalanced. How, then, shall we account for its
enormous number of eggs?

There is one stage of its existence which we have not yet
examined. Serious dangers assail it while it is stillin the egg,
and here, probably, is the secret of its excessive fertility. The

* Once, when wishing to mark a number of social wasps (Vespa maculata),
which we had caged, we liberated afew at a time in our wire-enclosed porch, and
then catching them with gloved hands, cut their wings. At the time there were three
or four individuals of A. cophinaria in the porch and many of the wasps were lost by
becoming entangled in their webs. The spiders bound them up very quickly, show-
ing no sign of fear. V. maculata is, of course, far from being so redoubtable an
enemy as the solitary wasp.

74 PECKHAM. [Vol. 1.

cocoons of cophinaria, though a little smaller, closely resemble
in shape and color the oak-apple, Quercus inanis,which abounds
among red oaks; but if this is a case of protective resemblance,
which seems improbable since cophinaria inhabits open, marshy
places and is not found in the woods, the disguise is far from
being a complete protection. Each cocoon contains many hun-
dreds of eggs, but among them a wholesale destruction is carried
on by cophinaria’s most dangerous enemy, the ichneumon fly.
The cocoons are hung among the long grass and are not difficult
to find, but when opened they so frequently contain nothing but
young ichneumons as to make it reasonable to believe that
where the enemies of other species slay their hundreds this one
enemy of cophinaria slays its thousands. *

Another, and perhaps the most serious of all the dangers
to which this species is exposed, is the flooding of the marshy
land upon which the cocoons are deposited. During the pres-
ent spring we collected 62 cophinaria cocoons, some of which
were in a fragmentary condition. Of the whole number 26
contained live spiders, 6 contained eggs just about to hatch,
24 had been destroyed by parasites and 6 by water. In the
marsh where the full-grown spider is most abundant in
August, every bush being covered with them, we found only
three water-soaked cocoons. When they are destroyed by para-
sites the case remains, but when the water spoils them they are
probably decayed, broken up and washed away, seldom leay-

* Of 406 cocoons of this species taken in one spring by Prof. Wilder, 134 were
entire; 190 were pierced, but contained live spiders; 59 were torn, probably by birds,
most of them still containing some of the spiders, and 23 contained the remains of
parasites by which the young spiders, or the eggs, had been destroyed.—American
Association for Advancement of Science, Vol. Xxm, p. 261,

Prof. Wilder thinks that the young spiders devour each other to a considerable
extent, as they are shut up for weeks or months after they are hatched with no food
but one another. Young spiders, however, probably do not eat until after about the
second or third moult,and although those that he observed did eat each other they
were under unnatural conditions, and must have grown less rapidly and remained
longer in the cocoon than they would had they been left out of doors, as even with
our late Wisconsin spring we find the young of cop/inaria running about, half grown,
in June.

The eggs of this species are also open to the attacks of another spider
Emerton has found the young of P. morsitans in cocoons of cophinaria (Note
Hentz’s Spiders of North America, p. 58.)

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 75

ing a trace behind. This recalls Prof. Wilder’s suggestion that
the immense fertility of Nephila plumipes is counter-balanced
by the destruction of its cocoons, which are so placed, depend-
ing from leaves, that great numbers of them are washed away
and destroyed by rain.

Let us look at the Attidee. In this family the most fertile
species on record is Phidippus morsitans, laying about 180
eggs; while the least fertile is the little, ant-like Synageles
picata, laying three.

So far as defending itself from the attacks of enemies of
its own class is concerned, morsitans has an unquestionable
advantage. It has not only superior agility; it is also one of
the largest and fiercest of the family, and it is improbable that
any other spider preys upon it; while nothing more defense-
less can be imagined than the little picata, with its tiny body,
weak falces and slender legs. The fierceness of morsitans,
however, would be useless against such foes as birds and wasps,
while the strongly contrasted black and white of its coloration
make it conspicuous.

Beyond the fact that it is small and dark-colored, picata
has absolutely nothing to protect it excepting the resemblance
which it bears to an ant. Can this alone gives the species so great
an advantage that it is enabled to maintain itself with as low a
birth-rate as three or four in a season ?

We must accept one of two alternatives. The direct
relation between mortality and multiplication is well estab-
lished, and it is plain that no species could maintain itself
with so low a birth-rate were not its mortality correspondingly
low. It must, then, either have practically no enemies, or its
means of protection from its enemies must be uncommonly
efficacious. We cannot accept the first alternative. No crea-
tures are exposed to the attacks of more enemies and none are
more helpless under such attacks than small, soft-bodied
spiders; and the conclusion seems unavoidable that picata
enjoys immunity from attack because it appears to be not a
spider but an ant.

76 PECKHAM. [Vol. 1,

A species, then, may depend for its preservation upon
either active or passive means of protection, the passive means
often outvaluing the active. But whatever the means may be
—fierceness, inedibility, protective resemblance, or mimicry—
I would suggest that one test of its efficiency may be found in
the fertility of the species.

DIRECT PROTECTION.
Resemblances to Vegetable and Inorganic Things.

As a general rule the forms and colors of spiders are adapted
torender them inconspicuous in their natural homes. Bright
colored spiders, except where sexual selection has been at work,
either keep hidden away or are found upon flowers whose tints
harmonize with their own. This rule, while it has numerous
exceptions, is borne out by the great majority ofcases. A good
illustration is found in the genus Uloborus, of which the mem-
bers bear a deceptive resemblance to small pieces of bark or to
such bits of rubbish as commonly become entangled in old,
deserted webs. The only species in our neighborhood is Uloborus
plumipes,which I have almost invariably found building in dead
branches, where its disguise is more effective than it would be
among fresh leaves. The spider isalways found in the middle of
the web, with its legs extended in a line with the body. There
has been, in this species, a development along several lines,
resulting in a disguise of considerable complexity. Its form and
color make it like a scrap of bark, its body being truncated and
diversified with small humps, while its first legs are very
uneven, bearing heavy fringes of hair on the tibia and having the
terminal joints slender. Its color is a soft wood-brown or gray,
mottled with white. It has the habit of hanging motionless in
the web for hours at a time, swaying in the wind like an inani-
mate object. The strands of its web are rough and inelastic,
so that they are frequently broken; this gives it the appearance
of one of those dilapidated and deserted webs in which bits of
wind-blown rubbish are frequently entangled. The web repre-
sented in Plate IV was unusually perfect, and yet did not
appear as it does in the drawing. The pattern was made out by

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. TT

using a magnifying glass and turning the branch from side to
side, only two or three of the radii being visible from any one
point of view. The web, moreover, is builtin such a place that
the spider is easily confounded with the objects among which
it is seen.* To these characteristics we must add its habit of
making a number of roughened grayish or brownish cocoons,
and of so disposing them in the web, either heaped one above
another or strung along tip to tip, that they seem tobe nothing
more than a mass of rubbish.

Out of seven examples of the species taken during one
summer, five were found in dead tamarack branches, one on a
dead bush, and the seventh, an interesting variety, under the
eaves of a porch. My eye was caught by what seemed to be a
string of eleven cocoons (it is not common to see more than four
ina web). On attempting to take them down I was surprised
to see one of the supposed cocoons begin to shake the web vio-
lently. Ten were what they seemed to be, but the eleventh was
the mother spider, whose color and general appearance was
exactly like that of the little cases that she had made for her
‘eggs.

The plumipes which is represented in Plate IV was
brought from a tamarack swamp and placed on some dead
branches in the corner of a porch. She proved a most patient
little model, hanging in one position all day long. When the
drawing began she had one cocoon; two more appeared at
intervals of three days. She lived in the porch for several
weeks. At one time, becoming dissatisfied with her position,
she raised her cocoons seven inches, to a higher crotch in the
branch, and there built a new web. She moved rather slowly.

From the descriptions of U. productus, U. borbonicus and
U. Walckeneerius, these species must be close to plumipes in
shape and general coloring, in habits, in the character of their
webs and in the form and color of their cocoons.

* Simon says of this species: “Il s’établit soit sur les broussailles séches, soit
dans les trous des vieux murs; il se tient toujours les pattes étendues longitudinale-
ment et se confond avec les objets sur lesquelsilest placé.” Arachnides de France,
Vol. I, p. 169.

78 PECKHAM. [Vol. 1.

Near to Uloborns is Hyptioides, in which is found the same
kind of protective resemblance. The little brown spider, H.
cavatus, is So inconspicuous that no ordinary observer ever sees
it, and even when his attention is called to it he takes it to be a
bit of dirt. Looking closely, we find it to be of a light, yellow-
ish gray, with several dark humps and lines; while the
legs and cephalothorax are blackish. It usually crouches,
with its legs drawn in, at the end of a branch, holding the
elastic thread which runs to its web, and in this positien it is
all but indistinguishable. Emerton has noticed that it is col-
ored like the ends of the dead pine branches among which it
usually lives. *

In many ways similar to H. cavatus, is H. paradoxus. Of
this species Thorell says: “The identity of color between the
animal and the dry branches causes it not to be so easily
perceived.” + /

Among the Epeiride there is no prettier instance of pro-
tective form and habit than Cyrtophora conica, the little spider
which we once taught to recognize the sound of the tuning-fork.
Its color is gray, broken with irregular lighter and darker
lines, and its abdomen, behind, has a rounded projection. ‘This
neutral coloring and irregular outline give it the same adyan-
tage as that possessed by Uloborus and Hyptioides, and like the
former genus it strings its cocoons across the web; but it is pro-
tected in a still higher degree by its habit of accumulating a
quantity of light rubbish, remains of insects, ete., which it
places in a band across the web, binding all together with some
loose strands. ‘The cocoons are partly hidden in this mass of
débris, and they, as well as the spider itself, standing at the
central point, appear tobe a part of it. This resemblance is
extremely close—so much so that although we visited the
little spider before referred to at least once a day for several
weeks we were frequently deluded into thinking she was gone,

* New England Spiders of the Family Ciniflonidae, Trans. Connecticut Acad .,
Vol. VIII, 1888, p. 456.
| Huropean Spiders, Part I, p. 7.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 79

a close inspection being necessary before she could be distin-
guished.*

The same kind of resemblance is found in the genus
Argyrodes. These spiders are usually of parasitic habit, build-
ing in the corners of webs of larger species. ‘Two of them are
common in this country, fictilium and trigonum. They are
small and slender, with elongated bodies. Of trigonum Mr.
Emerton says: “These spiders live among the upper threads
of the webs of Agelena, Linyphia and Theridium and are most
common in woods of pine and spruce. They look, in the web,
like straws, or still more like the scales from pine buds, which
are often caught in the same webs.” + We find it in Wiscon-
sin, on the ground among the grass. Fictilium has not been
found in the web. We have caught it always in a swampy
piece of ground, where the long grass is partly green and
partly dead and yellow. In this locality its slender, yellowish,
elongated body affords it good protection.

A foreign species, A. epeiree, is referred to by Cambridge
as follows: “It appeared to have spun its own little irregular
snares among the mazes of the Epeira’s webs, in which it sat,
looking like a little morsel of dead stuff, and perhaps deluding
the other spiders into a belief that it was so, and thus escaping
being devoured.” {

In Ariamnes attenuata (fig. 2, see p. 80), the abdomen is
still more elongated than in Argyrodes. This species is also
yellowish in color and is probably protected by its resemblance
to a straw or blade of dead grass. Many related forms have
been described by Simon, Taczanowski and others.

* While the (. conica of Menge seems to be identical with (, caudata Hentz,
his description of the web as from seven to ten feet wide, and stretching from tree to
tree, does not at all correspond to the web of the American species, which does not
exceed twelve or fifteen inches in diameter. ‘The measurements that he gives seem
strangely out of proportion to the size of the spider, which is only 8 mm. long.

Menge says that Lister, who first observed the habits of this species, thought
that the remains of insects which the spider had devoured were hung across the web
as trophies of victory. Prewssische Spinnen, p. 76.

{New England Spiders of the Family Therididae, Trans. Connecticut Academy,
Vol. VI, 1882. p. 24.

} Spiders of Palestine and Syria, Proc. Zool. Soc. 1872, Part I, p. 279.

80 PECKHAM. [Vol. 1,

Similar in many respects to the Argyrodes group are the
Tetragnathine. These spiders are all slender, and, whenever
they are at rest, keep their legs extended in a line with the
body. Their usual position is on a branch at one side of
the web. ‘Their col-
oring runs through
the shades of brown,
yellow and green,
and they are frequently mottled or lined with black or white.
Mr. Atkinson speaks of a Tetragnatha (probably grallator) which
mimics elongated, dark blotches on grass stems; he says: “I
have often seen them,when frightened, leave the web and, cling-
ing to a grass-stem, place their bodies close to the stem, stretch-
ing the anterior legs above and the posterior ones below. The
body being dark and the legs green. the spider was well
protected.” *

_ In some species of Tetragnatha, as in Argyrodes, the tip of
the abdomen is elongated and turned upwards.

We come now to a large and interesting class in genus
Epeira. I refer to those species, mostly nocturnal, which are
protected during the day, not by hiding in crevices nor in any
way actually getting out of sight, but by the close resemblance
which they bear to the bark of the trees to which they cling.
This resemblance is brought about in two ways; through their
color, which is like that of wood or lichens, and through their
tuberculated and rugose
forms, which resemble rough
bark.

One of the most remarka-
ble of these forms is C. mitra-
lis, a Madagascar species,
which, looked at in profile,
probably resembles a woody
knot. The abdomen is divided into two divergent cones
(fig. 3). The entire upper surface of the body is covered

Fig. 2.—Ariamnes attenuata (from Cambridge).

Fig. 3.—Cerostris mitralis (from Vinson).

*J quote from some manuscript notes which Mr. Atkinson has kindly allowed
me to make use of.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS 81

with conical elevations, which render it rough and uneven;
the sides of the abdomen are made up of several layers, which
form stages, one above another, like the ridges of bark on a
woody exerescence. The legs, formed
of wide, flattened plates, make the base.
The color of the spider is yellowish-
gray, varied with white and dark red-
dish-brown. It has the habit of perch-
ing on a branch and clasping it like a
bird,* so that the elaborate modifica- 4
tion of form, which would be useless if Tins 4 Cerostris mitralis,
the spider hung exposed in the web, is Rn ergal pty ee
made as effective as possible.

To take an example nearer home, E. infumata is a large,
round-bodied spider, with two humps on the abdomen, which
Emerton describes from New England as being brown, mottled
with white and black; he adds that when it draws in its feet it
looks like a lump of dirt. Infumata, in Wisconsin, has always
a good deal of bluish green on the upper surface of the abdo-
men. ‘This may be a variety which has been so developed as
to resemble the lichens which cover the tree to which it clings.
It is one of the spiders which bear a good deal of handling
without uncurling its legs, or showing any sign of life. Its
humpy form and its color give it a very inanimate appearance.
It is rather common in our neighborhood and may be caught
in the late twilight while building its web, but to search for it
in the daytime, even among the trees that it most frequents, is
an almost hopeless task. A more grotesque form is E. stellata, in
which the abdomen has not two, but twelve or fifteen humps.
These are so disposed that the edge of the abdomen, all around,
is scalloped. The colors are light and dark brown, modified by
gray and white hairs. This spider remains motionless during
the daytime, keeping its legs drawn up to its body. It is com-
mon on grass and low bushes. It is not found in Wisconsin,

Vinson, loc. cit., p. LITT.

82 PECKHAM. [Vol. 1,

but the description of it suggests a resemblance to a piece of
dead leaf.

There are many other spiders in this genus that have
humps and are colored in brown, gray or dull yellow, as nord-
manii, angulata, solitaria, ete. It is an almost universal habit
among the Epeiridee to drop to the ground when threatened,
and when a humped gray or brown spider drops to the ground
and draws in its legs it is nearly indistinguishable from the
lumps of earth, sticks and stones that surround it.

One of the Therididze which has the
same protection is Ulesanis americana*
(fig. 5). The abdomen, which covers
the cephalothorax nearly to the eyes,
has a prominent hump in the middle
of the back and four or five others
behind. Its color is in shades of brown

Tig. 5.—Ulesanis ameri- gnd low.
cania (from Emerton). al yel OW

Analogous to the humped Epeiridee
is Thomisus foka, of Madagascar, a spider which is regarded
with great terror by the natives, as being so poisonous that even
its breath is deadly. They say that cattle, when about to lie down,
look carefully about to see if one of these spiders is in the neigh-
borhood. This dread is, no doubt, inspired by the strange and
uncanny aspect of a perfectly harmless creature. It has a
rugose, tuberculated body of trapezoid form, the colors being
brown and reddish, while the whole aspect is crab-like. The
thick, short legs are reddish, covered with tubercules. The
secret of its strange form is made clear when we learn that it
resembles in color and general appearance the fruit of Hym-
enea verrucosa, a tree common in the forests where this spider
is found. ¢

Among the curious forms which must have been developed

* This species, Emerton says, looks like a seed or a luinp of earth.

! Vinson, loc. cit., pp. 70-71.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 83

through advantageous variation, but which we are unable to
explain, is Eriauchenus workmanni (fig. 6).

_ Epeira prompta (a variety of parvula, Plate IV, fig. 2) isa
common spider in Wisconsin. It is most frequently seen on
cedar bushes, where its color harmonizes with
that of the foliage and fruit. During the day
it usually rests on a branch near its web. The
back of the abdomen is of a peculiar bluish-
green, exactly like that of the lichens growing g

waving black lines which imitate the curling youpmayy, (rem
edges of the lichens. The one represented

in the plate was found on an old cedar which was covered
with lichens. It was kept for two weeks in a glass-covered
box, where it spent most of the time crouching in a corner.
It built no web, but spun some irregular lines to run about
on. It ate gnats, flies, and once a little jumping spider, S.
pulex, which we were keeping in the same box, leaping upon
its prey, as noted by Hentz,* like an Attus. This seems a
curious habit to be acquired by an Epeirid, since these spiders,
as we have noticed among our captives, are usually dependent
for food upon what is caught in their webs. Prompta moves
awkwardly, but very rapidly.

Drapetisca socialis, while quite a different looking spider, is
protected in the same way—by its resemblance to the bark
upon which it lives. Emerton speaks of finding it on the bark of
spruce trees, which it “closely resembles in color.”+ Menge says
that it is common in Prussia, where it is seen in great numbers
on fir trees, whose spotted bark it resembles in color, so that it
is not easily seen.{ We have found them, most commonly,
upon birch trees, and in this situation their color adaptation
is perfect. Both the spider and the peeling bark of the tree are
of a light silvery brown, covered with little blackish marks.

*“This very distinct species is very active after sunset, running with great
speed, and leaping like an Attws. Itis motionless during the day.” Loc. cit., p.112.

+ New England Theridide, p. 67.

{; Preussische Spinnen, p. 142.

84 PECKHAM. [Vol. 1,

On the bark these marks are, of course, irregular, while on the
spider they form a pattern made up of straight and curved
lines and dots, the legs being silvery, barred with blackish.

Another little Theridion that is found on birch bark has
the same colors arranged a little differently. The abdomen
above has a large and peculiarly irregular black patch, which
shades off into mottled brown and black on the sides and below.
The cephalothorax has stripes of brown and black, and the legs
are barred with light and dark brown.

Spiders that live upon walls, fences, tree trunks, or on the
ground harmonize in color with the surfaces upon which they
are found, being usually gray, brown or yellow, mottled with
black and white. This proposition is so well established* as to
need but few illustrations. The Therididee furnish many
examples, as T. murarium, a gray spider varied with black and
white, said by Emerton to live usually “under stones and
fences, where itis well concealed by its color”; and Lophocarenum
rostratum, a yellowish brown spider, found among leaves on the
ground. Among the Attide bright sexual coloring often gains
the ascendancy over the protective tints, yet this family gives
us good examples in such speciesas M. familiaris and 8. pulex.

To these may be added an as yet undescribed species
which we discovered last season in a neighborhood that we had
searched thoroughly for eight summers. We found the new
spider in great numbers, but could only detect it by a close
scrutiny of the rail fences on which it lived, its color being dark
gray.

Among the Lycosidze we have scores of dull-colored species
that live on the ground. Vinson refers to L. vulcani, which is
of a smoky black color and which lives in the crater of a
volcano, saying: “Its sinister color seems to conform to its

* Dr. McCook says: “Spiders that nest in stables, houses, on fences, etc., ordin-
arily have dusky colors harmonious with the environment.”’—WNotes on Relations of
Structure and Function to Color Changes in Spiders, Proc. Acad. of Natural Sciences
of Philadelphia, 1888, p. 174. See also Cenni sulle colorazioni e forme mimetiche utili
nei ragni, by Prof. P. Pavesi, in Atti d. Societa Ital. d. Scienze Nalurali, Vol. XVIII,
1875,

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 85

habitat.” * A more peculiar example is D. sex-punctatus, which
is said by Dr. McCook to have a tint like that of the water
upon which it is constantly found.+

In the Thomiside we find the rule holding good through
whole genera with scarcely an exception, as with Xysticus and
Synema, whose members, colored yellowish brown or gray,
haunt fences and tree-trunks. These spiders, moreover, often
haye the body very much flattened, so that they the more
easily escape notice and can readily conceal themselves by
slipping into cracks and crevices.

In the Drassidze we have the same resemblance, as in H.
ecclesiasticus, a gray spider found running on walls, and in H.
bilineatus, whose distinct black and white would seem to render
it conspicuous, but really have the opposite effect on the stony
beaches where it is found.

A spider of another family, Hersilidia lucasii, is spoken of
by Cambridge as follows: “Their position is usually with the
legs extended flat upon the under side of the stone, with the
sandy-yellow, mottled color of which the color of the spider
so admirably agrees that it requires a practiced eye to
detect it.” {

Another general rule is that spiders living in dark places
are dull-colored, usually having more or less livid white,
mingled with gray,as Pholcus phalangoides, which is pale with
dark bands, and is common in cellars; or Meta menardi, which
is dull brown and yellow with light stripes, and lives in damp,
shady places or in caves. Many species of Clubiona come
under this head. They have commonly pale or livid coloring
and are found under bark or stones, in caves, etc.

Turning from these to the brightly colored spiders the
most obyious instances of protective coloring are the green
species which live on leaves. Such are Lyssomanes viridis and
many other Lyssomane, which are of a faded yellow color in

* Loc. cit., p. 16.
+ Loe. cit., p. 174.
t Catalogue of a Collection of Egyptian Spiders, Proc. Zool. Soc., 1876, p, 568,

86 PECKHAM. [Vol. 1,

alcoholic specimens, but which, lam told by Mr. Herbert Smith,
are of a bright green in their tropical homes. Olios viridis and
Linyphia viridis* come under thisclass. The former is entirely
“of a tender yellowish green” and is found on the leaves of
orange trees. The latter has both male and female of a tender
green color and is found on the leaves of rose bushes.

Pavesi enumerates the following green species which live
on leaves: Micromata virescens (CI.), Epeira cucurbitina (Cl.), Ther-
idium viride Nic., Dictyna viridissima (WIk.), Clastes viridis WIL.,
Peucetia viridis (Blkw.), Attus pistacius.+

The spiders which imitate the colors of flowers are found,
to a great extent, among the Thomiside; and here a point of
interest must be noted. The resemblance of Epeiridee and Ther-
idide to the surfaces upon which they are found are simply
protective. It is useful in preserving the spider from enemies,
but does not assist it in capturing prey. In the Thomiside, on
the other hand, the protective disguise serves a double purpose,
and it seems probable that it is fully as great an advantage to
them to deceive their prey as their enemies.

No family can show more brilliant and beautiful colors
than the Attide. Wallace speaks of them in the tropics as
being so exquisitely colored as toresemble jewels rather than
spiders.{ Yet no cases have been cited in which spiders of
this family imitate the colors of flowers; and from what we
know of the mating habits of our own bright colored Attide
there can be little doubt that these jewel-like spiders also owe
their beauty to sexual, and not to natural selection.

It is probably: to Thomiside that Bates refers when,
in speaking of spiders with showy colors, he says: “Some
double themselves up at the base of leaf-stalks, so as to resemble
flower buds, and thus deceive insects on which they prey ;” §
and again: “Some hunting spiders mimic flower buds and sta-

* Vinson, Loc. cit. pp, 103 and 277.
+ Loe. cit., p. 2.

t Tropical Nature, p. 97.

§ Loc, cit. p, 54,

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 87

tion themselves motionless in the axils of leaves and other
parts of plants to wait for their victims.” *

Mr. Herbert Smith also refers to this habit. He says:
“Some of the spiders, we find, are excellent imitators. The
cylindrical species lie extended in their webs, with the legs
stretched out, to look like astick; round-bodied kinds draw their
legs close and look like a leaf-bud, or a ball of their own silk
entangled in the web. * * How shall we notice this one that
sits on a leaf, all in a heap; the pink three-lobed body appears
just like a withered flower that might have fallen from the tree
above ; to the flies, no doubt, the deception is increased by the
strong, sweet odor of the spider, like jasmine.” +

Trimen gives several instances in which Thomisids mimic
flowers. He says: “Many species of Thomisus are well adapted
to succeed by being colored in resemblance to the flowers in
or on which they await the arrival of their victims. One that
inhabits Cape Town is of the exact rose-red of the flowers of the
oleander; and to more effectually conceal it, the palpi, top of
cephalothorax, and four lateral stripes on the abdomen, are
white, according remarkably with the irregular white markings
so frequent on the petals of Neriwm.

“T was led to notice a yellow spider of the same group, in
consequence of seeing that two of a number of butterflies on the
flowers of Senecio pubigera did not on my approach fly off with
their companions. Each of these unfortunates turned out to be
in the clutches of a spider, and when I released them I observed
their captors very narrowly, and I found that the latters’ close
resemblance to the Senecio flowers was not one of color alone,
but due also to attitude. This spider, holding on to the flower-
stalk by the two hinder pairs of legs, extended the two long
front pairs upward and laterally. In this position it was scarcely
possible to believe that it was not a flower seen in profile, the
rounded abdomen representing the central mass of florets, and
the extended legs the ray florets; while, to complete the illusion,

* Lepidoptera of the A mazon Valley, Trans. Linn. Soc., Vol. XXXII, p, 509.

+ Loe. cit., p. 221.

88 PECKHAM. [Vol. 1,

the femora of the front pair of legs, adpressed to the thorax,
have each a longitudinal red stripe which represents the
ferruginous stripe on the sepals of the flower.

“On another occasion I witnessed the actual capture of a
small blue butterfly (Lycenesthes) by a white spider of the same
genus. The butterfly was engaged in honey-sucking on a white
flower-head of Lantana, and explored each individual flower
with its proboscis. While I was watching it, the butterfly
touched and partly walked over what looked like a slightly
folded or crumpled flower about the middle of the cluster.
This turned out to be a spider, which instantly seized the butter-
fly, throwing forward its front legs somewhat after the fashion
of a Mantis. In this spider the effect of the little depressions
on the limb of the corolla was given by some depressed lines on
the back of its smooth white abdomen.” *

Among our own Thomisidee we have a pretty example of
flower copying in Misumena vatia, a very variable little spider,
which is usually golden yellow, living upon the yellow flowers
of our fields. Sometimes it is light green, when it is found
upon low trees and bushes, and sometimes light pink, living
upon wild roses. Each variety is a perfect match, in color, for
the leaves upon which it is found. Pavesi says that this species
when living on flowers is white, or white or yellow with red
stripes on the abdomen; but that when found among the grass
it is grass-green, with dark, obscure stripes on the cephalothorax
and palpi.t

Bright spiders seem to feel the necessity of keeping out of
sight more than dull-colored ones. Thus such bright Epeiridee
as insularis keep hidden, during the day, in tents by the side of
the web, only coming down into the center at night. Bright
Theridide, as frondeum, usually live under leaves. This seems
to hold even with Attide. I have noticed among those kept in
captivity that while the dull-colored ones ran about in the box,

* Roland Trimen, Protective Resemblances and“Mimicry” in Animals, p.- 4.

+ Loc. cit., p. 5.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 89

the brilliant male splendens passed his entire time curled up in
a corner under a sheet of web, seeming very morose and sulky.

Cambridge notices a peculiar case of protective resemblance
among the Thomiside. This is T. setiger, whose abdomen,
covered with spines and bristles, is whitish mingled with yellow.
He says: “The peculiar clothing of long, pale spines and
bristles affords an evident protection to this and the preceding
species (‘I’. buffoni), making them look exactly like bits of coarse,
fleecy wool, or the rough seeds of some plant or other; had I
not observed them moving, they would probably have escaped
notice.” *

The last instance that I shall cite is a predaceous spider
which is disguised from both its enemies and its prey by an
elaborate combination of form,
color, position and character of
web. I refer to Ornithoscatoides
decipiens (fig. 7), first described
by Forbes and afterwards by Cam-
bridge, the latter author giving in
the same paper descriptions of
three other species of the same
genus, whose habits have not been
noted, but whose protection is evi- Pee Ooo pantiosea toldes) deat:
dently of the same order as that

of decipiens. I give Forbes’ interesting account of his capture
of decipiens, quoting also the remarks by which Cambridge pre-
faces his description, since his explanation of the gradual deyel-
opment, through Natural Selection, of the spider’s deceptive
appearance applies as well to all the cases of protective disguise
which have been here enumerated.

The capture is described as follows:

“On June 25th, 1881, in the forest near the village of Lam-
par, on the banks of the Moesi river in Sumatra, while my ‘boys’
were procuring for me some botanical specimens from a high
tree, I was rather dreamily looking on the shrubs before me,

* Spiders of Palestine and Syria, Proc. Zool. Soc., 1872, Part I, p. 308.

90 PECKHAM. (Vol. 1,

when I became conscious of my eyes resting on a bird-excreta-
marked leaf. How strange, I thought, it is that I have never
got another specimen of that curious spider I found in Java
which simulated a patch just like this! I plucked the leaf by
the petiole while so cogitating, and looked at it half listlessly
for some moments, mentally remarking how closely that other
spider had copied nature, when, to my delighted surprise, I
discovered that I had actually secured a second specimen, but
the imitation was so exquisite that [really did not perceive how .
matters stood for some moments. The spider never moved while
I was plucking or twirling the leaf, and it was only when I placed
the tip of my little finger on it, that I observed that it was a
spider, when it, without any displacement of itself, flashed its
falces into my flesh.

“The first specimen I got was in W. Java, while hunting
one day for Lepidoptera. I observed a specimen of one of the
Hesperidee sitting, as 1s often a custom of theirs, on the excreta
of a bird on a leaf; I crept near it, intending to examine what
they find in what one is inclined to consider incongruous food
for a butterfly. JI approached nearer and nearer, and at last
caught it between my fingers, when I found that it had as I
thought become glued by its feet to the mass; but on pulling
gently the spider, to my amazement, disclosed itself by letting
go its hold; only then did I discover that I was not looking ona
veritable bird’s excreta. * * The spider is in general color white,
spotted here and there with black; on the underside its rather
irregularly shaped and prominent abdomen is almost all white,
of a pure chalk white; the angles of the legs are, however, shining
jet-black. The spider does not make an ordinary web, but
only the thinnest film on the surface of the leaf. The appear-
ance of the excreta rather recently left by a bird on a leaf is
well known. ‘There is a pure white deposit in the centre, thin-
ning out round the margin, while in the central mass are dark
portions variously disposed; as the leaf is rarely horizontal, the
more liquid portions run for some distance. Now, this spider
one might almost imagine to have in its rambles ‘marked and

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 91

inwardly discerned’ what it had observed, and to have set
about practicing the ‘wrinkles’ gained; for it first weaves a small,
irregular patch of white web on some prominent leaf, then a
narrow streak laid down towards its sloping margin ending in
a small knob; it then takes its place on the center of the irregu-
lar spot on its back, crosses its black-angled legs over its thorax,
and waits. Its pure white abdomen represents the central
mass of the bird’s excreta, the black legs the dark portions of
the slime, while the web above described which it has spun
represents the more watery marginal part (become dry), even
to the run-off portion with the thickened knob (which was not
accidental, as it occurred in both cases), like the residue which
semifiuid substances ending in a drop leave on evaporation.
It keeps itself in position on its back by thrusting under the
web below it the spines with which the anterior upper surfaces
of the legs are furnished.”*

In answer to the idea that the supplementing of the color
and form of the spider by its peculiar web almost implies
consciousness,+ Cambridge says:

_ “Tt seems to me, on the contrary, that the whole is easily
explained by the action of Natural Selection, without supposing
consciousness in the Spider in any part of the process. The web
on the surface of the leaf is evidently, so far as the Spider has
any design or consciousness in the matter, spun simply to secure
itself in the proper position to await and seize its prey. The
silk, which by its fineness, whiteness, and close adhesion to the
leaf causes it to resemble the more fluid parts of the excreta,
would gradually attain those qualities by Natural Selection, just
as the Spider itself would gradually, and probably pari passu,
become, under the influence of the same law, more and more
like the solid portion.” ¢

We may repeat, in regard to this species, what Wallace has

* On the habits of Thomisus decipiens, by H. O. Forbes, Proc. Zool. Soc., 1883,
p. 586.

+ Mr. Forbes has especially disclaimed any idea of consciousness on the part
of the spider.

1 On two new Genera of Spiders, Proc. Zool. Soc., 1884, p. 197.

92 PECKHAM. [Vol. 1,

said about a butterfly which imitates a shrivelled leaf: “We
thus have size, color, form, markings, and habits, all com-
bining together to produce a disguise which may be said to be
absolutely perfect.” *

PROTECTIVE HABITS.

Going along with these forms of protective resemblance,
we find certain habits which sometimes serve independently to
protect the spider, but oftener are supplemental to color and
form. Many species hide in crevices or in leaves which they
roll up and bind together at the edges. In the Epeiridz some
are like thaddeus, which makes a little tent of silk under a leaf
near its web. The young thaddeus also makes a tent, but spins
its little geometrical web on the under side of the leaf, the
edges being bent downward. E. insularis has the more common
habit of forming its tent by drawing the edges of two or three
leaves together with strands of web; in this it sits all day, but
at night descends and occupies the center of the web during the
hours of darkness. I have often found it in this position when
hunting nocturnal species by lantern light. It is probable that
in tropical countries the monkeys, and perhaps the birds,which
devour these large Epeiridze have learned to recognize their
webs, which are very large and conspicuous, and to trace them
to their hiding places close by; and thus may have arisen the
curious habit noticed by Vinson as possessed by E. nocturna
and E. isabella of destroying the web each morning and rebuild-
ing it at night;+ the spider in this way gaining greater security
from diurnal enemies.

Atypus abbotii builds a purse-shaped tube which is found
attached to the bark of trees, and which has the external sur-
face dark and covered with sand.{ The trap-doors which close
the nest of some of the Territelarice are wonderful examples of

* Natural Selection, p. 61.
+ Loe. cit., p. CXIII.

t For acomplete account of this species see Nesting Habits of the American
Purseweb Spider, by Rev. Henry C. McCook, Proc. Acad. Nat. Science of Philadeldphia,
1888, p. 203.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 93

protective industry. They fit with such absolute accuracy into
the openings of the nests and are so covered on the upper side
with moss, earth, lichens, ete., as to be indistinguishable from
the surrounding surface.

The rectilinear lines which are stretched in front of the
webs of many Epeirids are useful in taking and sending on to
the spider the shock which tells of an approaching enemy.
Some spiders, when danger threatens, shake the web so vio-
lently as to grow indistinct to the eye, and others, as Pholcus
atlanticus, hang by the legs and whirl the body rapidly with the
same bewildering result.

Mr. Herbert Smith gives me the excellent suggestion that
the sideways movement of the Thomiside, or Laterigradz, has
a direct protective value, since the enemies of spiders are accus-
tomed to allow for a forward, but not for a lateral movement of
their prey.

A habit common to many spiders, especially among the
Epeiride, is that of dropping to the ground at the approach
of danger and resting motionless among the dirt, sticks,
leaves, etc., which they resemble in color. The holding of the
body in some peculiar position, as in Uloborus, Hyptioides, and
the flower-like Thomiside, is a necessary accompaniment to the
color modification.

The cocoons of spiders are seldom left exposed and unpro-
tected. We find them in corners and crevices, concealed in
rolled up leaves or under bark. Very often the cocoon itself
is covered over with a sheet of web. In some families the
mother carries it about with her attached to the underside of the
abdomen. In others she carries it in her falces until the young
are hatched. The cocoons of others, as Uloborus, Argyrodes,
ete., while hung out in the web are still concealed by deceptive
form and color, or by being covered with rubbish.

Cambridge speaks of A. brunnea,whose cocoons “are covered
over very soon after they are made and the eggs deposited in them,
with a coating of clay, which effectually destroys all their form
and beauty. This coating of clay answers probably two ends:
first, the concealment of the cocoon and its protection from

94 PECKHAM. {Vol. 1,

insect enemies; and, secondly, the protection of the eggs from
the too powerful rays of the sun, dry clay being (as is well
known) one of the best non-conductors of heat.” *

The peculiar cocoon of C. bisaccata is described by Emerton}
as follows: “Only one specimen of this (bisaccatw) was found
on a beech tree at New Haven with two cocoons. These were
dark brown, as dark as the bark of the tree and as hard.
Around the middle of each was a circle of irregular points. One
of the cocoons was attached by a strong stem to the bark, and
the other was attached in a similar way to the first cocoon.
The spider held on to one of the cocoons.” In this instance the
egg has evidently the same protection as that possessed by the
gray, bark-haunting spiders, with the added advantage of
hardness.

The habit of distributing the eggs through a number of
cocoons made at intervals of several days, is protective. In this
way, although one or two of the cocoons may be pierced by the
ichneumon, there is a chance that part of the brood may
survive. {

INDIRECT PROTECTION.

The indirectly protected group includes those spiders
which are rendered inedible by the possession of sharp spines
and chitinous plates, and also those that mimic other specially
protected creatures.

The females of the specially protected group are character-
ized by the following attributes:

Their inedibility, which they owe to a more or less coriace-
ous epidermis and an armature of strong sharp spines (fig. 8,
see p. 95).

Their brilliant colors—glistening black and white, yellow,
fiery gold, metallic silver, rose-color, blue, orange and blood-red.

Ann. and Mag. of Nat. Hist., Feb., 1887, p. 118.
New England Epeiride, p. 325.

EE. sancta benedicti Vinson makes as many as thirteen cocoons. Vinson,
loc. cit., p. 204. Oyrtophora bifurca McCook sometimes makes fourteen, which, like
the mother-spider, are light-green incolor. Proc. Acad. of Nat. Sci. of Philadelphia,
1887, p. 342.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 95

Their habit of hanging always exposed in the center of
the web.

In an interesting discussion of the protective value of color
and marking in insects, Poulton says that “the smaller conver-
gent groups of nauseous
insects often present us
with ideally perfect types
of warning patterns and
colors—simple, crude,
strongly contrasted-—every-
thing subordinated to the
paramount necessity of be- .
coming conspicuous,” the
memory of enemies being
thus strongly appealed to.

This proposition is well
illustrated by the Gastera-
canthide. Among larve the warning colors are almost invari-
ably black and white, or black (or some very dark color), in con-
trast with yellow, orange and red.* These are the colors that
also constantly recur among the Gasteracanthide.

Fig. 8.—Gasteracantha crepidophora (from
Cambridge).

I will cite a few species as illustrative of the general color-
ing in the group.

G. lepida Camb., Proc. Zool. Soc., 1870, p. 821. “The
upperside is of a bright, rich, orange yellow, with two broad
parallel transverse bands of blood-red tinged with carmine. *
* * The abdomen might almost be described as alternately
barred on the upper side, with transverse bars of red and
yellow.”

Phoroncidia awrata Camb., (Plate III, fig. 4). Referred to
by Butler, Proc. Zool. Soc., 1882, p. 766, as follows: ‘Four
examples of this rare and extremely beautiful species were
obtained. * * ‘Two of these are typical, their abdomen being

* Heperimental Proof of Protective Value of Color and Markings in Insects,by
E. B. Poulton, Trans. Ent. Soc., 1887, p. 230.

*Poulton, Joc. cit., p. 281.

96 PECKHAM. [Vol. 1.

of a fiery golden color, with black spines upon red bases; the two
others are considerably larger, and the abdomen is of a metal-
lic silver color, the spines black with red-brown bases and the
ocellations black.”

Paraplectana thorntoni Blk., referred to by Cambridge,
Proe. Zool. Soc., 1879, p. 293.

“The jet-black ground-color of the abdomen, with its

somewhat raised, large and conspicuous bright-yellow mark-
‘ings, and yellow cephalothorax, render it one of the most
striking and handsome known spiders of this family.”

G. alba Vinson, loc. cit., p. 240. Milk-white, with the
glisten and polish of porcelain. A dorsal stripe of a beautiful
black in the middle, dividing the shell into two equal parts.

G. helva Blk., described by Cambridge. Proc. Zool. Soc.,
1879, p. 287. Yellow or yellow-brown, with the spines of a
deep, rich, shining steel-blue color.

The Gasteracanthidee are not all brilliantly colored ; many
are of a light écru tint, with black spots and spines, but even
in these the smooth, glistening character of the shell gives them
a certain degree of brightness.*

Cases that may be more justly considered exceptions to the
rule that these hard, uneatable spiders are conspicuous are such
species as Acrosoma rugosa (fig. 9, see p. 97). One of this species
was sent me by Mrs. Treat last summer. It lived for several
weeks in my window, making no regular web, but hanging
among a few irregular strands. It ate nothing, although pro-
vided with insects, but drank greedily of water. It might
seem that its black and white coloring would make it conspic-

*Alcoholic specimens of this group usually lose their bright colors. Thus we
have a number of species described by Cambridge (Proc. Zool. Soc., 1879) as “dull
yellowish-brown,” “blackish-brown,” etc., but the author warns his readers that in
his opinion alcoholic and more especially dried specimens of Gasteracanthide lose
their original brightness. Hesays: “Weare probably therefore, in nine cases out of
ten, totally ignorant of the true colors and markings of the Gasteracanthides. ”-
P, 280,

He then goes on to note, in proof of this proposition, the case of an African
species which had been described as of a uniform, dull, muddy, brown hue, which, in
life, has a shade of “the loveliest and most delicate yellow, scalloped at the edges,
where occurs a dainty moulding of blue.”

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 97

uous, but in connection with its irregular shape and its way of
hanging motionless in the web it had the opposite effect.

We have no reason to suppose that the class represented in

rugosa is like that touched upon by Poulton, in which very
protectively colored larvee
suddenly assume a terri-
fying aspect on the near ©
approach of an enemy;
still they do enjoy a kind
of double protection.
They are inconspicuous,
and thus likely to escape
attack, but in case they
are attacked they have
sil ithe aclveniinge alt Say Sete adder any
being quickly rejected.
This experience cannot be as fatal to them as to the soft and
thin-skinned laryee. Their hard covering and projecting spines
would protect them to such an extent as to give them a fair
chance of surviving.

In one respect the inconspicuous Gasteracanthide have a
decided advantage over their bright colored relatives. The
birds, indeed, avoid the conspicuous ones, but their brilliancy
serves to attract another enemy against which spines are no
protection—the hunter wasp, which, as we have seen in the
work of Bates, sometimes provisions its nest wholly with
spiders of this family. Mr. Smith gives like testimony,
saying :

“Spines on the abdomen of certain spiders would serve as a
protection against vertebrate enemies, though they do not pro-
tect against the hunter wasps, which frequently provision their
nests with these species.” He adds, however, that most of the
Spiny spiders are common, and that their colors make them
conspicuous; just as butterflies that are protected by an odor
are common and bright-colored.*

*Letter on Enemies of Spiders-

98 PECKHAM. [Vol. 1,

Taczanowski says that A. horrida (PI. III, fig. 5,). is very
like rugosa, and adds that he considers this species as transitory
between Hpeira and Acrosoma.

Cambridge remarks upon the great variability in the
length and direction of the spines in individuals of the same
species of Gasteracantha.* Vinson notices the same character
in regard to the color of at least one species.t That variability
in the spines is found also in Acrosoma, is illustrated in Plate
Ill, where figures 1 and 3 represent extreme forms of the
female of A. spinea, the former being found in the northern
and the latter in the southern
part of the United States. A.
oblonga (fig. 6) is given to show
the sharpness of the spines in
some of these species.

The sexes in Gasteracantha
and Acrosoma are entirely dif-
ferent. The males are small,
sometimes very minute, and lack
both the spines and the brilliant
color of the females (fig. 10, and
Plate III, figs. 1,2 and 3). In-
deed, they resemble the females
so little that for many years
the relations between the two
were undiscovered. In the
genus Gasteracantha, up to so
The en Ee Iie m dive aa 187, eally tro
(rom, Marx). males had been described,
against one hundred and seventy females. {

This disparity has come about through the different habits
and functions of the female. Wallace has shown that among
insects the females often acquire protective colors which are

* Proc. Zool. Soc., 1879, p. 279.
+ Loc. cit., p- 241.

,

{ Cambridge, Proc. Zool. Soc., 1879, pp. 279 and 281.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 99

lacking to the males, because long life in the females is of
greater importance to the species than long life in the males.*

This applies also to the Gasteracanthidee where the females
are much larger, much more inedible, and much more conspic-
uous than the males. Wallace, however, limits his proposition
to cases where the modification is for concealment, and illustrates
it by instances among butterflies where the female alone mimics
some nauseous species. The Gasteracanthide are an exception
to his rule, that in groups which have a protection of any kind
independent of concealment, sexual differences of color are
either quite wanting or slightly developed.; That I do not
misinterpret his meaning is shown by the fact that after stating
thisrule he goes on to enumerate several cases in which specially
protected species have the sexes almost or quite alike.

In Gasteracantha and Acrosoma the habits of the female
as well as her functional importance call for some special
protection. She is much exposed, remaining in her weball the
time, while the male passes most of his life in concealment.
Thus the female of A. spinea, though not so gaudily colored as
many others, is easily recognized, and is constantly seen on low
bushes during the summer. At about the first of August the
males appear, quite suddenly and in large numbers, and may
be seen running about the leaves and branches near the webs
of the females. ‘Toward the end of the month they disappear.
Acrosoma and Gasteracantha are so near together that this
tends to prove the correctness of Cambridge’s surmise that the
males of the latter genus are short-lived. {

* “The comparative importance of the sexes varies much in different classes of
animals. In the higher vertebrates, where the number of young produced at a birth is
small and the same individuals breed many years in succession, the preservation of
both sexes is almost equally important. * * * Jn insects the case is very different;
They pair but oncein their lives, and the prolonged existence of the males is in most
cases quite unnecessary for the continuance of the race. The female, however, must
continue to exist long enough to deposit her eggs in a place adapted for the develop-
ment and growth of her progeny. Hence there is a wide difference in the need for
protection in the two sexes; and we should therefore expect to find that in some cases
the special protection given to the female was in the male less in amount or altogether
wanting.” A. R. Wallace, Natwral Selection, p. 112.

+ Loe. cit., p. 113.

{This shortness of life iscommon in the males of the Attide, In several spe-
cies it is almost impossible to find the male, whichis very common earlier in the
season, after the first of August, although the females are still numerous.

100 PECKHAM. [Vol. 1,

In at least two genera of the Gasteracanthide, then, there
is a difference between the sexes, which is the result of the
inheritance of special protective modifications by the female
alone.

In replying to Wallace’s theory that color differences
between the sexes are due to the keeping down for protective
purposes of the color of the female, Darwin says: “I do not
wish to deny that the female alone of some species may have
been specially modified for protection.”* In most cases when
the female is dull and the male bright colored it is difficult or
impossible to show that the difference has resulted from the
greater need of protection in the female. ‘The difference in the
Gasteracanthidee, however, is just such a case as was referred
to by Darwin, since it is unquestionably due to natural and not
to sexual selection.

The young of Gasteracantha and Acrosoma present certain
pecularities. Darwin’s propositions in regard to differences
between the two sexes in birds are as follows:

“Whenever and in whatever manner the adult male differs
from the adult female, he differs in the same manner from the
young of both sexes. * * *

“When, on the other hand, the adult male closely resem-
bles the young of both sexes (these, with rare exceptions, being
alike), he generally resembles the adult female.” +

Acrosoma and Gasteracantha are not included in these
rules, since although the young are alike at the very first, both
resembling the adult male, the young females very early begin
to vary toward the form and color of the adult female; so that
we have the young males and females resembling the adults of
the same sex, while the adult male and female differ greatly
from each other.

Darwin notes the occasional occurrence of such cases as
this in the following words:

“As variations occurring late in life, and transmitted to

*Descent of Man, p. 321.

+Zoc. cit., pp. 232, 283.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 101

one sex alone, have incessantly been taken advantage of and
accumulated through sexual selection in relation to the repro-
duction of the species; therefore, it appears at first sight an
unaccountable fact that similar variations have not frequently
been accumulated through natural selection, in relation to the
ordinary habits of life. If this had occurred the two sexes
would often have been differently modified, for the sake, for
instance, of capturing prey, or escaping from danger. Differ-
ences of this kind between the two sexes do occasionally occur,
especially in the lower classes. But this implies that the two
sexes follow different habits in their struggles for existence,
which is a rare circumstance with the higher animals.”*

In the Gasteracanthidee we have the necessary conditions
for the production, by natural] selection, of a difference between
the sexes early in life, 7. ¢., the habits of the sexes are distinctly
different, the males living in some place of concealment, while
the females soon begin to sit exposed in the web. It is
naturally of the greatest importance that the young females,
while adopting the habits of the adults, should acquire also her
special protection of form and color.

The variation in the female, although entirely due to
natural selection, probably first occurred in the adult, since
variations occurring early in life tend to be inherited by both
SeXes.

MIMICRY.

Mimicry, or the imitation of animal forms, while it isa
form of indirect protection, differs in no essential respect from
the imitation of vegetable and inorganic things. As Bates has
said, the object of mimetic tendencies is disguise, and they will
work in any direction that answers this purpose.}

In nearly all respects spiders come under the three laws
given by Wallace, as governing the development of mimetic
resemblances in several large classes. These laws are as follows:

1. In an overwhelming majority of cases of mimicry, the

*Zoc. cit., p. 241.
+Lepidoptera of the Amazon Valley, Trans. Linn. Soc., Vol. XXIII, p. 514-

102 PECKHAM. [Vol. 1,

4

animals (or the groups) which resemble each other inhabit the
same country, the same district, and in most cases are to be
found together on the very same spot.

2. These resemblances are not indiscriminate, but are
limited to certain groups, which, in every case, are abundant
in species and individuals, and can often be ascertained to have
some special protection.

3. The species which resemble or “mimic” these dominant
groups, are comparatively less abundant in individuals, and are
often very rare.*

The second and third of these laws are confirmed by what
we know of mimetic resemblances among spiders. They
mimic ants much oftener than other creatures, and ants are
very abundant, are specially protected, and are much more
numerous than the mimetic spiders. To the first law, also,
they conform to a great extent, since everything tends to show
that in tropical America and in Africa the ant and the spider,
the one mimicked and the other mimicking, are always found
together. So far as I can discover, however, the ant-like
spiders of North America, are not found in company with any
species of ant which they resemble. This may be because they
do not mimic any particular species, but only the general ant-
like form; or, considering that the genera which contain their
nearest relatives are much more abundant in Central and
South America, it may be that these forms were originally
tropical, mimicking some tropical species of ants, and that after
the Glacial Epoch they migrated northward, leaving the ants
behind them. However this may be, their peculiar form has
served them well, since they have maintained themselves as
fairly abundant species with a lower fecundity than is found in
any other group of spiders.

The cases in which one species mimics another may be
divided, according to the kind of benefit derived, into four
classes: Class 1. Asa rule, where we find one species mimick-
ing another, the mimicked species possesses some special means

*Natural Selection, p- 76.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 103

of defense against the enemies of both. ‘This defense may
consist of a disagreeable taste or odor, as in the Heliconide,
which are mimicked hy other butterflies; of some special
weapon of offense, as where wasps and bees are mimicked
by flies and moths, or posionous vipers by harmless caterpillars;
or of a hard shell, as where the coriaceous beetles are
mimicked by those that are soft-bodied.

Instances of this rule are exceedingly numerous; indeed,
Wallace says that specially protected forms are always mim-
icked ; still we have nothing mimicking our Gasteracanthide.

Class 2. The mimetic may prey upon the mimicked spe-
cies, its disguise enabling it to gain a near approach to its vic-
tims ; as the mantis, mentioned by Bates as exactly resembling
the white ants upon which it feeds; and the flies which mimic
bees, upon which they are parasitic, and are thus able to enter
the nests of the bees and lay eggs on the larve.

Class 3. The mimetic species may, by its imitation, be pro-
tected from the attacks of the creature it mimics, as is the case
with the crickets and grasshoppers which mimic their deadly
foe, the hunter wasp.

Class 4. The mimetic species may prey upon some crea-
ture which is found commonly with and is not eaten by
the mimicked species.

No two of these classes are mutually destructive so that in
any case of mimicry a double advantage may be gained.

Let us see which of these advantages has directed the
development of mimetic tendencies among spiders.

While among beetles and butterflies we most commonly
find mimicry of one species by another within the same order,
we have no instance of a spider mimicking another spider.*
This may be accounted for by the fact that the specially
protected spiders depend for their safety upon the possession of
hard plates and spinous processes, and although the hardened
epidermis might be imitated (we know that hard-shelled beetles

* The spiders instanced by Pavesi (loc. cit., p- 7) which resemble other genera

rather than their own, such as Nephila tetragnathoides, Tetragnatha epeirides, etc.,
cannot, it seems to me, be classed properly under mimicry.

104 PECKHAM. [Vol. 1,

are mimicked by others that are soft), spines could scarcely be
imitated by a soft-bodied creature with sufficient accuracy to
insure disguise.

While spiders most commonly mimic ants, we hear also of
their imitating beetles, snail-shells, ichneumons and horse-flies.
There is also a curious Madagascar species which looks exactly
like a little scorpion, the resemblance being heightened by its
habit of curving its flexible tail up over its back when irritated.

Those that resemble beetles comprise nearly all the species
of the genera Coccorchestes and Homalattus. These are small
spiders with short, convex bodies. The abdomen fits closely
over the cephalothorax and the epidermis, which has usually
a metallic lustre, is sometimes coriaceous. Striking exaimples
are found in H. coccinelloides, which bears a strong resemblance
to beetles of the family Coccinelloidze and in C. cupreus, in
which certain marks on the abdomen imitate the elytra of
beetles.

The following account of a spider which mimics a snail-
shell is given by Mr. G. F. Atkinson:

“An undescribed species of Cyrtarachne* mimics a snail-
shell, the inhabitant of which, during the summer and fall, is
very abundant on the leaves of plants in this place. In the
species of Cyrtarachne the abdomen partly covers the cephalo-
thorax, is very broad at the base, in this species broader than
the length of the spider, and rounds off at the apex. When it
rests upon the under side of a leaf with its legs retracted it
strongly resembles one of these snail-shells by the color and
shape of its abdomen. The two specimens which I collected
deceived me at first, but a few threads of silk led me to make
the examination. The spider seemed so confident of its protec-_
tion that it would not move when I jarred the plant, striking it
several hard blows. I pulled the spider forcibly from the leaf,
and it did not exhibit any signs of movement until transferred
to the cyanide bottle.” +

*(, multilineata.

|New Instances of Protective Resemblances in Spiders, American Naturalist,
June, 1888, p. 545.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 105

Cambridge, in the Hine. Brit., says that a species of Cyrtar-
achne, found in Ceylon, resembles a small molluse and that
some of the genus Erysoma are very like a minute crab, giving
E. cabinde as an example. But he does not seem to imply
that the crabs are actually mimicked, and he gives no details.
Stoliczka describes a small Xysticus which both in form and color
strongly resembles a minute crab, but the habits of the spider,
which was always found inside of flowers, preclude any idea
of mimicry.

Trimen gives an account of the imitation, by spiders, of
horseflies, a case falling into class 2, as follows:

“Hunting spiders are in some cases very like their prey,
as may everywhere be noticed in the case of the species of
Salticus which catch horseflies on sunny walls and fences.
The likeness is not in itself more than a general one of size,
form and coloring; but its effect is greatly aided by the actions
of the spider, which walks hurriedly for short distances, stop-
ping abruptly, and rapidly moving its falces, in evident mim-
iery of the well-known movements so characteristic of flies.”

Instances of spiders mimicking ants are very numerous,
and in many cases the resemblance is so close as to, at first
sight, deceive a trained naturalist. This resemblance is
brought about by the spider’s body being elongated and
strongly constricted, so that it appears to be composed of
three segments instead of two, by the color, by the way in
which the spider moves about, zig-zagging from side to side
like an ant, and by its habit of holding up one pair of its legs
and moving them in such a way that they look exactly like
the antennee of an ant.

Ants may be regarded as specially protected, by their
sharp, acid flavor, and in some species by the possession of
stings or of horny processes.

On the ground that there are birds which do eat ants, and
eat them greedily, it has been thought by some naturalists that
they cannot be considered specially protected creatures, and
that, as spiders can therefore derive no protection from mim-

u@

106 PECKHAM. [Vol. 1,

icking them, all cases of such mimicry depend upon the spi-
der’s increased ability to capture the ants as prey, but Iam
convinced that this is too hasty a conclusion. It is unquestion-
ably true that some birds feed almost exclusively upon ants,
but these are the exceptions. It is a common thing to find that
specially protected groups, which are safe from the attacks of
most creatures, have their special enemies. Thus, even the nau-
seous Heliconide are preyed upon by certain spiders and wasps;
and bees, in spite of their stings, are preferred to other insects
by the bee-eaters. Moreover, the ant-deyouring birds are found
largely among the wood-peckers, which eat the ants that run on
the trunks of trees, and are therefore not a source of danger to
the ant-like spiders, the American species of which, so far
as I can learn, live entirely upon the ground.

In the United States comparatively small numbers of
either ants or spiders are eaten by birds, but in tropical Amer-
ica there are enormous numbers of humming-birds feeding
almost exclusively upon spiders, and there the protective
advantage of looking like ants must be of great importance
to the smaller species.

Belt considers that the advantages gained by ant-mim-
icking Central American spiders lies entirely on the side of
protection. In relation to this subject he says: “ Ant-like
spiders have been noticed throughout tropical America and
also in Africa. The use that the deceptive resemblance is to
them has been explained to be the facility it affords them for
approaching ants on which they prey. I am convinced that
this explanation is incorrect, so far as the Central American
species are concerned. Ants, and especially the stinging spe-
cies are, so far as my experience goes, not preyed upon by any
other insects. No disguise need be adopted to approach them,
as they are so bold that they are more likely to attack a spider
than a spider them. Neither have they wings to escape by fly-
ing, and generally go in large bodies easily found and ap-
proached. ‘The use is, I doubt not, the protection the disguise
affords against small insectivorous birds. I have found the

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 107

crops of some humming-birds full of small, soft-bodied spiders,
and many other birds feed on them. Stinging-ants, like bees
and wasps, are closely resembled by a host of other insects;
indeed, whenever I found any insect provided with special
means of defense I looked for imitative forms, and was never
disappointed in finding them.”*

The ant-like species are probably protected by their
appearance from the attacks of many of the larger spiders.
We have kept great numbers of Attidee in captivity, and,
although they devoured flies, gnats, larvee, and other spiders,
they would never touch ants. Among spiders, however, as
among birds, we find that certain groups subsist almost entirely
upon ants.+

The class of spiders whose mimicry protects them from
their enemies, whether they are birds or other spiders, probably
includes at least two of our own ant-like species, Synageles
picata and Synemosyna formica, which, in confinement, are
always hungry for gnats, but will not touch ants, even of small
Size.

The existence of a class of spiders which mimic the partic-
ular species of ants upon which they prey is not to be questioned,
but it is doubtful whether the benefit to the spider is increased
facility in capturing the ant, or whether it is merely protective.
It may be that the spider, by virtue of its resemblance to the ant,
not only gets an abundant supply of food, but also escapes being
eaten itself, and thus enjoys a double advantage. Both Bates
and Wallacet take the ground that the advantage derived by

* Toc. cit., p. 314.

+Dr. McCook tells me that ZL. formidabilis pitches her tent over or near the
formicary of the powerful agricultural or stinging-ant of Texas, P. barbartus, and
captures the insects as they climb the stalks of ant-rice. He also says that J. tepi-
dariorum devours large numbers of ants, and he has seen them eaten by A. fasciata.
Simon also gives an interesting account of the depredations committed upon ants by
spiders of the genus Enyo, Arachn. de France, Vol. I, p. 243.

tBates says: “There are endless instances of predaceous insects being disguised
by having similar shapes and colors to those of their prey ; many spiders are thus
endowed.” Lepidoptera of the Amazon Valley, p. 509; and Wallace: “There isa
genus of spiders in the tropics which feed on ants, and they are exactly like the ants
themselves, which, no doubt, gives them more opportunity of seizing their prey.”
Natural Selection, p. 98.

108 PECKHAM. [Vol. 1,

the spider consists in greater ease in the capture of prey, but
both of these writers refer to spiders only incidentally to illus-
trate a general proposition, without special consideration of
their peculiar conditions.

Mr. Herbert Smith, who has paid a good deal of attention
to this subject, is inclined to believe that the mimicry in ques-
tion is entirely protective. He writes as follows:

“In the United States there are a few rare spiders that
mimic ants. Here at Taperinha we find a good score of species
of these spiders aping the various kinds of ants very closely ;
even the odd, spiny wood-ant, cryptocerus, furnishes a pattern,
and there are spiders that mimic the wingless ichneumons. We
find, after awhile, that the spiders prey upon ants just as our
spiders catch flies; indeed, this fact has already been noted by
other observers. But we goa step beyond the books when we
discover not only that the spiders eat the ants, but that they
eat the particular ants which they mimic. At all events, we
verify this fact in a great number of cases, and we never find
the spiders eating any but the mimicked species. * * * I
do not like to hazard a theory on this case of mimicry. It is
difficult to suppose that the quick-witted ants would be deceived
even by so close a resembiance; and, in any case, it would seem
that the spiders do not require such a disguise in order to
capture slow-moving ants. Most birds will not eat ants; it
seems likely, therefore, that this is simply another example of
protection; the spider deceives its enemies, not its prey; it
mimics the particular species that it feeds on, because it is seen
in that company when it is hunting, and among a host of
similar forms is likely to pass unnoticed.” *

At first sight, and especially in view of the fact that such
cases are not uncommon among insects, it would be naturally
supposed that the object of the mimicry was to enable the
spider to approach its victim without exciting suspicion ; and it
is difficult to account, on any other supposition, for the very
close resemblance between certain species of spiders and the

* Loc. cit., p. 223,

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 109

particular species of ants which they prey upon. It seems as
though the highest point of protective benefit would have been
reached long before the resemblance of the spider to the ant
had become so close as it really is. On the other hand, it is
difficult to believe that ants are deceived, even by those spiders
which mimic them most closely, when we remember that
their perceptions are so keen that they discriminate not only
between ants of their own and different species, but even between
ants of their own species living in two different communities.*

The mimicry of ichneumon flies by spiders was noted
some years ago by Mr. Herbert Smith. This case comes under
Class 3, in which one species mimics another which preys upon
it. Great destruction is caused by ichneumons which lay their
eggs on the bodies of the live spiders, and the disguise probably
protects the spider by leading the fly to mistake it for one of its
own species.

We have no proof that spiders ever mimic ants as a
method of escaping from them, but it is possible that this
sometimes happens. We know that some ants prey upon
them. The foraging ants of South America destroy spiders as
well as many kinds of insects, and Wallace mentions a small,
wood-boring ant which fills its nest with small spiders.+

If the spiders that feed upon ants deceive them by their
mimicry those which are preyed upon by ants would gain
an advantage by a similar disguise. I once placed a little ant-
like spider of the genus Herpyllus in a bottle with three ants no
larger than itself, which I had caught with it in the sweep-net.
In a very few minutes the ants had killed and began to de-
vour the spider. It may be that the resemblance was suff-
ciently close to deceive them in the open, but failed when
spider and ants were confined together in close quarters.

I will now give some account of an ant-like spider which
we have studied closely.

* Sir John Lubbock.
+ Tropical Nature, p. 83.

110 PECKHAM. [Vol. 1,

Synageles picata (fig. 11), while not a rare spider
with us, is not often caught in the sweep-net, as it usually
keeps close to the ground. One hot afternoon in July, how-
ever, while sweeping on a sunny, stony hillside, sparsely covered
with grass, I captured five females and
one male of this species along with eight
or ten ant-like beetles and a dozen or
fifteen small ants of two or three different
species. Being anxious to discover what
relations existed between these creatures,

Fig. 11.—Synageles pic- : 2 :
ata (from nature, by Mr. which, though belonging to different

L, Kumlien).
orders, bore so strong a resemblance to

each other, I put them all together in a glass-covered box.
The results of this experiment were negative. ‘The spiders,
while greatly interested in each other, paid but little
attention to the beetles and none at all to the ants. The ants
ran wildly about and seemed to be entirely absorbed in trying
to get out. The beetles took matters more philosophically and
kept quiet.

After several hours I put some gnats into the box.
These were caught and devoured by the spiders. A little later
I liberated the ants and beetles. The spiders lived in the box
in good health and spirits for the remainder of the sum-
mer. They were very fond of heat, running about very
actively as long as their box stood in the sunshine, but retir-
ing into their little, tubular nests as soon as it became cool or
cloudy.

While picata is ant-like in form and color, by far the most
deceptive thing about it is the way in which it moves. It does
not jump like the other Attide, nor does it walk in a straight
line, but zig-zags continually from side to side, exactly like an
ant which is out in search of booty. This is another illustra-
tion of what Wallace has shown in relation to butterflies—that
that which is an important functional structure in the
mimicked group may be imitated by the mimetic species,
even when the habits of the latter render it perfectly

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 111

useless.* The ant only moves in this way when it is hunt-
ing; at other times it goes in a straight line; but its little
imitator zig-zags always.

In addition to its ant-like walk, picata holds up its second
pair of legs in such a way that they appear likeantenne. The
first legs are short‘and support the anterior part of the body.
The second pair, although it is sometimes used, seems not to
be needed for locomotion. All the threatening and similar
movements made by other spiders with the first pair, are, with
picata, made with the second.

Spiders commonly remain nearly motionless while they
are eating ; picata, on the other hand, acts like an ant which is
engaged in pulling some treasure-trove into pieces convenient
for carrying. I have noticed a female picata which, after get-
ting possession of a gnat, kept beating it with her front legs as
she ate, pulling it about in different directions, and all the time
twitching her ant-like abdomen, Pavesi says that the ant-like
Drassidze and Attidze continually move their abdomens exactly
as ants do.t I have not noticed this habit in any of our
spiders excepting this species.

Picata is found in company with several small species of
ants, but does not seem to resemble one more than another. It
does not molest, and neither is it molested by the ants, so that
the cause of its mimicry must be looked for in either Class 1
or Class 4. I should not have formed this latter class, in which
it is supposed that one species mimics another because it preys
upon a third species found with the mimicked form, but not
eaten by it, had it not been suggested to me by the fact that
when, as before related, I captured the spiders, ants and beetles
together, one of the spiders (picata) was engaged in eating a
tiny beetle. It may be that picata preys upon some small
beetle which is not eaten by ants—possibly one of those
which, undisturbed by the proprietors, inhabits their nests. In

* Natural Selection, p. 91.
+Loe. cit., p. 12.

112 PECKHAM. {Vol. 1,

this case the disguise of the spider wouid enable it to approach
the beetle without arousing suspicion. While I give this as a
possible explanation, it is improbable that any such disguise is
necessary in order to capture beetles, and I think it most likely
that the object of the mimicry is to preserve the spider from
some enemy that would rather eat spiders than ants.

To sum up the peculiarities of picata—it is ant-like in
form and color; it moves like an ant and holds up its second
pair of legs to represent antennee; it is found among ants, but
neither eats them nor is eaten by them.

Synemosyna formica (fig. 12) agrees
in all respects with picata, unless it is in
the zig-zag walk; upon that point I am
unable to speak with certainty. Of
formica, which is more ant-like in form
and color than picata, Hentz says: “I
had seen individuals of this species run-
ning on the blades of grass and stems of
weeds long before I distinguished them

Fig. 12.—Synemosyna !rom ants. They move with agility and

See ee neat? PY can leap, but their habitus is totally dif-

ferent from Attus. They move by a reg-

ular progression or regular walk, very different from the
halting gait of that subgenus.”*

Both formica and picata hold the second pair of legs like
antenne. Many of the ant-like Epeiride from South America,
seen in collections, have palpi that look extremely like anten-
nee, while their long legs can only be useful in locomotion.
Belt speaks of a spider in Nicaragua which holds up its first
legs like antennze and moves them about like an ant. He also
says that in one spider the palpi are lengthened and thickened
so as to resemble an ant’s head. The following quotation
from J. P. M. Weale, shows that some African ant-like species
also hold up their first legs: “The most perfect cases of mim-

*Loc, cit., p. 73.

No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 113

icry I know of are two spiders (specific name unknown to me)
which bear the closest resemblance to ants. They belong to
the Salticidee and are apparently related to S. formicarius.
The one is smooth, black and shining and runs rapidly on the
ground and bark of trees, and resembles the ant which builds
its nests in Acacia horrida and is used by the Kafirs for the
purpose of torture. The other is larger and has its cephalo-
thorax dull black and its abdomen covered with short yellow-
ish hairs. It is generally found running on the stems of her-
baceous plants and small bushes and closely resembles an ant
found in similar situations. The fore legs in both species are
larger than the second pair and are frequently held up, when
they closely resemble the antenne of ants. So exceedingly
close is the resemblance that at first sight I have nearly always
taken them for the imitated ants.”*

Among spiders, then, as among other arthropeds, we find
that some groups have reached a condition of close harmony
with their environment; this harmony being brought about
through the same modifications of color, form and habit as
those seen among insects, the common ends of capture of prey
and protection from enemies being thus attained.

*Natwre, 1871, Vol. III, p. 508.

ay,

Rethe®

are

PLATE I.

Habrocestum splendens: Male and female, to show the
difference between the sexes; first three moults, to show the
greater resemblance of the young to the female; variety of the
female.

Habrocestum peregrinum and Habrocestum auratum
males, to show the departure in that sex from the general
coloring of the genus; note that the female of splendens resem-
bles these males more than she does the male of her own
species.

Ht, splendens. ¢ Hf splendins. £

Vv
HH splendens.

7 moult

H. SPLEnaens.
FH moult.

He splendens.

2 moult

: Hauratunr §
H peregrinum £

From nature by Ludwig Aumlien.

ri py a Vea , rf

Bel

Rie get 2)
PEED ‘
ras poe o
ab fer? tee ;
ii
i y i)
if
e We orn fot ey
Als OT oe TaD Tt et he 3
cht. ee Se s
i aig
te hk me sre diy i‘ f
Ga
ne F 7
¥ if
‘ a7
. |

PLATE II.

Astia vittata: Female and two male forms, to show the
two varieties and the sexual differences.

Pseudicius harfordii: Male and female, to show the
sexual differences.

Phidippus cardinalis: To show the coloring in the
male.

Phidippus johnsonii: To show the coloring in the male.

Zygoballus bettini: To show the coloring in the female,
the male being still more brilliant.

iN

A vitlala var nger.

P harfordii £

P johnsoni.
A f Zbettinig

From nature by Ludwig Kumlien.

a Att, er

PLATE III.

Figures 1 and 3. Acrosoma spinea, two forms of female.

Figure 2. Acrosoma spinea, male.

Figure 4. Phoroncidia aurata, female.

Figure 5. Acrosoma horrida, female (from Taczanowski).

Figure 6. Acrosoma oblonga, female (from Taczanowski).

Note: By mistake, figures 5 and 6 were included as being
drawn from nature by Mr. Kumlien. They were, in reality,
copied from Dr. Taczanowski’s work, Araniedes de la Guyane

Francaise.

Sateen ab wal, del.

PLATE IV.

Upper figure: Uloborus plumipes in web, with one
cocoon, to show protective resemblance.

Lower figure: Epeira prompta, resting on lichen-covered
tree-trunk, to show protective coloring.

PLave IV.

LP
aa

Mumlon dad

MuKevalcon ad wal, del,

ii |

776