446 Mr. Newport on the Anatomy and 
duct (z) formed by the union of the deferential ducts of the two sides and of 
the seminal vesicles. At the point of union of the analogues of these parts in 
the female the passage is dilated into a large cecal cavity, from the closed 
end of which, on each side, proceed two diminutive czeca, the undeveloped 
representatives of the vesiculæ seminales (x) of the male. The dilated pouch- 
like cavity in the female, the so-called spermatheca, which receives and re- 
tains the influence of the male at the union of the sexes, is thus an enlarged 
uteroid expansion of a portion of the common oviduct which is formed by the 
union of the terminations of the deferential and seminal tubes of the male. 
This is the general anatomy of these organs, both in Pteronarcys and Perla; 
and to which that of all other Hexapods, subject to variations in the relative 
development of particular portions of these structures, is conformable. 
From this comparative examination of structure in Pteronarcys it may be 
asked, what are the proper affinities of the insects of this genus? and whether, 
with the other Perlide, they occupy a proper position in the arrangement of 
systematists? The great similarity of the digestive organs of Perla to those 
of the Blattide, and the remarkable existence of certain talc-like structures 
on the head in insects of this family external to the ocelli (fig. 10), resem- 
bling others which are known to exist at the base of the antenna in the 
Blattide, suggest the conclusion that if the Megaloptera, including Perla and 
Pteronarcys, are not joined to the Orthoptera, they ought at least to follow 
that Order, at the head of the Neuroptera, and to be succeeded by the Libel- . 
lule, Agrionide and Ephemeride, as the most natural arrangement, and as 
most conformable to their anatomy. 
