1965] 
Levi — Spider Genitalia 
155 
Boiling the female genitalia in 10% NaOH may be necessary to 
clear heavily sclerotized parts, but this method invariably distorts 
and warps structures, swelling softer parts. It should only be used 
as an additional method if there are many specimens. 
Among the numerous difficulties of taxonomic research in the 
family Araneidae (= Argiopidae) is the problem of matching males 
and females. They are often collected separately and may be different 
in appearance. Abalos recently (1963) observed, in his study of 
reproductive behavior of spiders, that during the mating of many 
species the tip of the male palpal embolus, presumably carrying sperm, 
breaks off and remains in the female genital ducts. Though this had 
been noticed before in black widows, it appears to be widespread in 
theridiid spiders and orb weavers. The reason it has been overlooked 
is that the majority of males collected are virgin, in search of a 
female ; the tip of the embolus is therefore still attached in most males 
preserved in collections. Because they die soon after mating, mated 
males are rarely collected. On the other hand, probably the majority 
of females collected have mated. In the genus Argyope J now being 
studied, and presumably in other argiopids, the tip of the male em- 
bolus can readily be “fished out” of the epigynum by jiggling the 
projecting parts with a needle. Among related species of the genus 
Argyope , these tips differ strikingly in structure, athough the female 
genitalia are quite similar. An illustration of a broken off tip was 
supplied by Petrunkevitch (1930) with the hope of finding a male 
to match it. These tips not only permit matching males with females, 
but facilitate identification of females that have similar epigyna. Of 
course, the assumption is made that the male chose a mate of his 
own species. But the same method, applied to species in which the 
female is as easily determined as the male, may provide some data on 
the frequency of mating between species in nature. 
I would like to thank Dr. A. M. Chickering, Mr. Jon Reiskind 
and my wife for editing, and Miss Vida Kenk and Mr. F. Vuilleumier 
for translating the summary. The investigations were supported by 
Public Health Service Research Grant AI-01944. 
Resumen 
Preparaciones microscopicas permanentes de los palpos y epiginios 
de aranas son desvantajosas ya que, al deshidratar las partes escle- 
rozadas se tuercen, se pueden destruir al secarse, y a menudo la 
preparacion es separada del resto del especimen guardado en alcohol 
y se pierde. Es mejor guardar los genitales en tubos pequenos (micro- 
