734 THE GENERATIVE ORGANS. 
without doubt with the progenital somite, and represent the 
anterior gonapophyses of the male. 
The manner in which the ventral portion of the genital 
somites is drawn forwards during development, so that the six 
papilla all appear to arise from the same place, renders it 
exceedingly difficult to trace the development of the individual 
elements of the ovipositor, or sting, and gives rise to the decep- 
tive appearance as to the relation of the bases of the parts, as 
those belonging to the posterior somites are frequently drawn 
further forwards than those arising from the anterior somite. 
The only certain criterion as to their nature is the position of 
the orifice of the sexual duct. 
The difficulty of accounting for the passage of the ova 
through the sting in the aculeate Hymenoptera, and through 
the narrow channel in the Terebrantia, has led to the view 
that the sexual duct opens either behind or in front of the 
sting. It certainly opens through the terebra, and I have 
sought in vain for any other opening of the generative duct in the 
aculeate Hymenoptera. In these Insects I suspect that the 
parts of the sting, or terebra, are separated during oviposition, 
although it is exceedingly difficult to understand how this 
occurs, as the parts are closely locked together when used as a 
borer or sting. The anatomy of the parts renders it certain 
that such a separation is effected in the Bees just as it is in the 
parasitic Hymenoptera, in which there can be no doubt the 
passage of the ova is through the terebra. The ova in the 
aculeate Hymenoptera do not, perhaps, pass through the whole 
length of the sting, but only through its base ; but the oviduct 
certainly neither opens in front of nor behind the base of the 
sting, but through its cavity. Kriipelin held that the external 
orifice of the oviduct is in front of the base of the sting, and even 
if this is the case, homology indicates that the latter is developed 
from the mesogenital, and not from the progenital, somite. If 
such an orifice exist, I cannot understand how I can have 
failed to discover it. 
The Penis.—It is well known that the efferent ducts of the 
gonads in the Crustacea are paired, and situated in the basi- 
