LUCY WRIGHT SMITH 
443 
In Pt. nobilis the structure is practically identical with this in 
Pt. dorsata. Pt. californica and Pt. princeps are liuilt on the same 
general plan. The inner part of the sperm-conveyer is much 
longer (text-fig. D, I), the free part more complicated (text -fig. 
D, F) and the cup (text-fig. D, C) smaller, but the filling of the 
sperm cup probably takes place as in Pt. dorsata. No tendons 
are conspicuous in Pt. californica or Pt. princeps. 
Figure D . — Pteronarcys princeps Banks. Supra-anal plate or sperm-con- 
veyer, in left lateral view. 
Pt. proteus and Pt. biloba represent another type of genitalia. 
Superficially the supra-anal plate appears to be totally different 
from that of the other group, but closer examination shows it to 
be made up of the same fundamental parts although somewhat 
modified in form and position. The inner part (fig. 11, I) is much 
the same aside from being a trifle more slender; the free end 
(fig. 11, F) is a direct prolongation of the inner part; it is a dor- 
sally flexed, chitinous rod somewhat flattened anterio-posteriorly. 
In pinned specimens the rod appears to be entirely chitinized but 
in well preserved alcoholics the posterior surface is covered by a 
thin, fleshy pad. Surrounding the free end posteriorly and 
laterally there is a pair of chitinized plates articulated to the 
median portion (fig. 11, P. G. P.). Their point of attachment 
marks the boundary between the inner and free parts. Just 
dorsal to the place of articulation there is a pair of thin, chitinous 
triangular processes which I have called lateral braces (fig. 11, 
L. B.). Bands of muscle (fig. 11, M) connect the lateral plates 
with the inner part. The paired condition of these lateral plates, 
the presence of the muscle binding them to the inner part, and 
the position of their point of attachment to the median portion, 
seem to indicate that they are homologous with Hagen’s “link” 
and “para-anals” in the Pt. dorsata type. They no longer lie 
vertically but have shifted to a horizontal position, the anus 
TRANS. AM. ENT. SOC., XLIII. 
