200 
Psyche 
[December 
In the present paper we describe an element of the embolus of the 
male that in some spiders is retained by the female in her seminal 
receptacle after copulation. We have found this element in some 
members of the families Theridiidae and Argiopidae. 
The following species of Latrodectus have been examined by us: 
mactans, curacaviensis , geometricus from Argentina, and mactans 
(— hasselti ) from Australia. In all fertilized females we have found 
in each seminal receptacle (figs, i, 20) one or more dark, sclerotized, 
flagelliform, slightly twisted pieces approximately 200 microns in 
length; with one end delicately pointed, the structure becoming pro- 
gressively wider toward its other end. The center of this structure 
is found to contain a longitudinal transparent tube, circular in sec- 
tion, and opening laterally near the pointed end ; at the opposite end 
the tube seems to be cut. 
Adult virgin females, reared individually in the laboratory never 
contained these elements; nor did females collected in the field and 
maintained in isolation without ovipositing (fig. 21). 
On examining unmated males we found the above mentioned ele- 
ment to be the tip of the embolus of the palpus (fig. 3). It is obvious 
that the transparent tube is the apical portion of what Comstock 
(1910) calls ejaculatory duct , and we shall refer to it here as the 
apical element. 
We wish to emphasize that females that had laid fertile eggs 
always were found upon dissection to contain the apical element, 
either within the seminal receptacle, at their entrance, or near them 
in the ducts. If virgin females of Latrodectus were placed together 
with males that had not mated and had the emboli complete (as 
observed under the stereoscopic dissecting microscope), it was found 
that after mating the apical element was found in the seminal recep- 
tacle and was now lacking in the males, having broken off during 
sperm transmission. 
When the apical element is found inside the seminal receptacle, the 
latter contains a granular seminal mass in which spermatozoa can 
be found. When the apical element is situated in the canals of the 
female, this seminal mass is found in the canal. We have never 
encountered the spermatic mass in females that did not also harbor 
the male apical element. 
The blind end of the palpal tubes of males whose embolus is com- 
plete contain the seminal mass; males that lack the apical portion of 
the embolus (those that have copulated), show only sperm residues 
in the tubes. 
Slide mounts of palpi of unmated males show distinctly the place 
