416 M. Leuckart on the Reproduction of Bark-lice. 



and conical ovipositor (undoubtedly the same structure that 

 Ratzeburg indicated as the penis, but which occurs in exactly 

 the same way in all individuals), we see a very inconsiderable 

 pedunculated pouch appended to the sexual passage. The stalk 

 of this organ is lined with a tolerably strong chitinous plate ; but 

 this covering gradually disappears towards the upper part, and 

 at last vanishes so completely that it requires great attention, 

 and particularly favourable preparation, to enable us to make 

 sure of the existence of a cavity in the interior. The wall of the 

 pouch consists of delicate, clear, vesicular cells. 



It would, of course, be most interesting to ascertain the phy- 

 siological signification of this organ, as by this means the ques- 

 tion would be decided whether these Bark-lice are or are not 

 furnished with a receptaculum seminis. For this purpose, un- 

 fortunately, I possess no data. I have never observed any pe- 

 culiar contents in the vesicle in question, nor have I ever dis- 

 covered it in other Aphides. If, under such circumstances, we 

 may suppose it possible that this represents a seminal receptacle, 

 on the other hand, its position and appearance are so little in 

 favour of this supposition that I am far more inclined to assert 

 that there is an entire absence of a seminal receptacle in our 

 Bark-lice. We are acquainted with many insects in which the 

 secretory appendages on the oviducts are increased (even in the 

 Cicada, which are allied to the Aphides, we meet with many 

 such structures) ; it is therefore possible that the Bark-lice may 

 be amongst this number. 



The lubricating glands which, in the Aphides, usually appear 

 as roundish pouches, and rarely (e. g. A. platano'ides) as long and 

 wide tubes, likewise differ in their organization in the Bark-lice. 

 Phylloxera possesses on each side (fig. 4) a cylindrical appendage 

 repeatedly notched, the short and stump-like branches of which 

 all lie in the same plane. The cellular walls are of considerable 

 thickness, and enclose a thin chitinous tube, which, at its lower 

 end, close to its insertion into the oviduct, becomes dilated into 

 a flask-shaped cavity. The contents of these tubes consist of 

 the same yellowish oil which is elsewhere met with in the lubri- 

 cating glands. It may be expelled by pressure from the tube 

 into the flask-shaped cavity, which is also usually filled with it, 

 and thence into the oviduct. At the point where the two acces- 

 sory glands open into the oviduct, the latter is of considerable 

 width. At the same place there is, in the interior of the oviduct, 

 a peculiar loop-like structure, which, on closer examination, 

 proves to be a narrow, much-curled, chitinous band, clothing the 

 oviduct in an annular form exactly at the level of the accessory 

 glands, and amalgamating on each side with the chitinous wall 

 of the flask-shaped oil-vesicle. This band does not, however, lie 



