1967] 
Pinter — Widow Spiders 
295 
tensity of red pigments in the preserving solution probably resulted 
from a greater abundance of soluble pigments in the ventral abdominal 
integument of No. 2 than in Nos. i or 3. 
390 480 570 
WAVE LENGTH nm 
Fig. 20. Color. Spectral curves of pigments of Latrodectus Nos. 1, 2 and 
Internal Genitalia. The importance of studying the internal varia- 
tions of the female genitalia of theridiids has been repeatedly stressed 
by Levi (1959, 1962 & 1965). The basic structural difference in 
the number of coils of the duct is illustrated in Figures 21 through 
24. No. 1 can easily be distinguished on the basis of one and a half 
to two turns of the duct. Figure 21 illustrates a duct with one and 
three-quarter turns. This compares with that of No. 1 of Abalos and 
Baez (p. 63). In the other populations the ducts are more complex. 
In Nos. 2, 3 and 4 the ducts make approximately three complete 
turns. In the four specimens of No. 4 the ducts make an additional 
quarter turn. One might best describe this situation as three and one- 
