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NORTH AMERICAN PLECOPTERA 
the abdomen and which is firmly bound by broad bands of muscle 
(text-fig. B, M) to the second part, a paired central piece called 
‘‘the link” by Hagen (text-fig. B, L). These muscles move the 
third part, the free end (text-fig. B, F), in a vertical direction. 
Between the broad, flattened, distal ends (“para-anal plates” 
Hagen) (text-fig. B, P. A. P.) of the link opens the anus. The end 
of the free part of the sperm conveyer is an inverted chitinous 
bowl or cup (text-figs. B and C, C) containing within itself a 
membranous, eversible sac (text-fig. C, S) with two tendon attach- 
ments; one, probably a protractile tendon, attached at the rim 
of the cup (text-fig. C, P. T.), noted by Hagen, and the other, a 
retractor, at the base (text-fig. C, R. T.), first noticed by Dr. 
Needham. 
Figure B . — Pteronarcys dorsata 
Say . Supra-anal plate or sperm-con- 
veyer, in left lateral view. 
Figure C . — Pteronarcys dorsata 
Say. Tip of sperm-conveyer showing 
membranous sac within, and everted 
from cup. After Hagen’s manuscript. 
The structure presumably operates as follows; by the contrac- 
tion of the muscles (text-fig. B, M.) the end of the penis is brought 
to the opening of the sperm ducts, then by a tightening of the 
protractile tendon the membranous sac is everted (text-fig. C, S) 
and with the suction accompanying its inversion, brought about 
by the retractile tendon, a sperm mass is drawn into the cup. 
This filling of the cup supposedly precedes copulation. Then in 
the same manner by eversion of the sac, the spermatozoa are 
probably transferred in copulation into the vagina of the female. 
