ee se ee le —_ 
MOULTING HABITS OF SPIDERS. 107 
the last moult is relatively so much greater, that one reasonably comes to 
locate the transformation within the last moulting period. In some cases, 
however, the coloration of the sexes is more strongly differenced during the 
stages previous to final moult. Thus the color of male Trochosas during 
the two or three last moults is notably clearer than that of females. With 
Attus, in the corresponding periods, one may observe the sexual peculiari- 
ties in color distinctly appearing, and that they deviate more and more 
intensely with each moult, until the last fixes the distinction. Like the 
male, the female awaits the final moult for perfect development, at which 
time the genital cleft is freely opened and the hood and scapus assume 
those various forms which serve as valuable specific characters. 
“Leidy,” one of my captive tarantulas, shed its skin several times. 
The first moult occurred some time in August (1882). I had been absent 
_ on my- usual summer vacation, and returning August 31st saw 
aaa Sa the animal lying on the soil about the middle of its araneary, 
jes: with its feet gathered together, looking dull, gray, and faded out, 
apparently dead. I shook the globe. No responsive motion fol- 
lowed, and I left without more careful observation, concluding that the 
spider was dead. I was not able to visit it again until the fifth day of 
September following. I threw off the cover of the globe and put my hand 
in to take out the dead body, which lay apparently in the same position, 
in order to preserve it in aleohol. At my touch the animal leaped to its 
feet, and as I hastily withdrew my hand it presented itself quite changed 
in appearance. The body was a fresh bright color, the cephalothorax a 
clean whitish gray, the head and fangs dark brown. The abdomen was 
black, with brown hairs covering it. The legs were black, with yellowish 
brown hairs and spines. I at once understood that the spider when first 
seen was in the torpid condition which usually immediately precedes the 
act of moulting. In the interval between my visits it had cast off its skin, 
which I found lying in a tolerably complete condition on one side of the 
glass. Another tarantula, a male, which I received when quite young, 
came to me a dull reddish brown, but during successive moults at last 
appeared a bright black brown, almost black. 
VIII. 
We may thus summarize the most important moulting phenomena, as 
above disclosed. 1. The first two moults of spiderlings occur within the 
cocoon or on the mother’s back; several occur before entrance 
ee upon independent life, sometimes as many as four, 2. The 
el individuals of a brood do not all moult at once, and those moult- 
ing first, having the greater strength, in some species feed upon 
the younger and weaker individuals; in these cases survival depends upon 
priority of moult. In other species cannibalism is absent or rare, and 
