POST-EMBRYONIC DEVELOPMENT OF CULEX. 189 
seem to take the place of vesicule seminales. In another 
enat, the genus of which I did not determine, the hinder 
portions of the vasa deferentia were swollen out to form 
large vesicule seminales, which arrangement however, I 
have not found in any of the Culices I have examined. 
The hinder parts of the two vasa deferentia, correspond- 
ing to the vesicule just mentioned are in Culex closely 
united together, and they are formed by invagination of 
the region which I take to be tenth sternum, or just behind 
it. The same invagination gives rise to the common 
pouch (or ejaculatory pouch), and the vasa deferentia 
‘ prostate 
¢ i) 
(hinder portions) are, as well as the elands, 
outgrowths of it. The walls of this portion of the vasa 
deferentia are thick and apparently glandular, and the two 
cohere closely, though transverse sections show their cavi- 
ties to be quite separate. The prostate glands are elon- 
gated bodies, extending forwards to the hinder part of the 
seventh segment. In transverse sections each is seen to 
have two cavities, which however unite behind before 
opening into the common pouch. 
Of the nature of the copulatory organ itself I am very 
uncertain ; apart from the two pairs of gonapophyses there 
is an Inner organ, on the under surface of which is the 
male genital aperture. This looks like a pair of fused 
appendages representing an eleventh segment of the abdo- 
men, but I do not feel justified in doing more than sug- 
gesting this as a possibility. As to the mode of use I am 
ignorant, having never seen it in use, but the best of my 
sections suggest that the hindermost portion of the ejac- 
ulatory duct, behind the common pouch, is eversible. 
