THE PUPAL STAGE OF CULEX. 69 



The common pouch is a dilatation of the ejaculatory duct at the base 

 of the copulatory organ, and the latter is perhaps derived from a 

 pair of abdominal appendages. 



The hinder parts of the vasa deferentia appear to be developed as 

 a forward outgrowth of the ventral wall of the common pouch, and 

 the prostatic glands are lateral outgrowths of the same. The 

 hinder part of each vas deferens is in some Culicidse expanded to 

 form a vesicula seminalis of considerable size, but this is not the 

 case in Culex. 



II. The female generative organs are a pair of ovaries, oviducts 

 uniting behind to form a median oviduct, a median copulatory 

 pouch and three spermathecse opening into the last. 



The ovaries correspond in size and position with the testes. 



The median oviduct is formed by invagination in the region which 

 I take to be the ninth sternum, while the anus opens at the posterior 

 end of what I take to be the eleventh segment, so that there is no 

 common cloaca. This invagination is already far advanced at the 

 beginning of pupal life (Fig. 7), and during this period it grows 

 forwards, keeping pace with the forward shifting of the last pair of 

 ganglia, and at all stages lying just behind it, till the final ecdysis, 

 when the rapid shifting of the ganglia leaves it behind. Its anterior 

 end is, in the adult, near the anterior end of the seventh segment. 



In the youngest pupse three flattened invaginations, the future 

 spermathecae, lie upon the dorsal wall of this median oviduct. 

 During the pupal period the anterior end of each becomes spherical 

 and acquires a strong chitinous lining. The anterior ends of these 

 organs remain stationary in the eighth segment throughout. 



The bursa copulatrix is a dorsal outgrowth of the invagination 

 which gives rise to the median oviduct, and is a small pouch lying 

 just behind and above the genital aperture. 



I am painfully conscious of the fact that the foregoing account of 

 this interesting pupa is far from complete, but the pressure of other 

 work prevents my adding anything considerable to it at present. 

 As soon as I have time to do so, I intend to work out the details of 

 the development of the eye, but fear it will not bo possible before 

 next summer. 



