DESCBIPTION OF PLATE F. 



Oviparous Aphis. 



Fig. 1. — Three chambers of an ovigerous fascicle, re- 

 duced from a figure by Huxley : e, epithelial layer ; g g\ 

 inner capsules of ovarian glands, which, originally 

 round, have by the natural lateral pressure become 

 elongated ; c, cord-like secretion of ovarian gland ; v, 

 germinal vesicle of a nascent ovum in the terminal 

 chamber; v', germinal vesicle of the second chamber 

 of the caecum. 



Fig. 2. — Portion of the walls of the ovisac, with its 

 epithelial cells, enclosing a nearly ripe ovum : y y 

 vitelline mass of the egg; s, clear space surrounding 

 the yolk (zona pellucida ?) ; e, epithelial coat of ovary. 

 From Gallipterus quercus. 130 diam. 



Fig 3. — One branch of the oviduct of another 

 example of the same species : v, vaginal tube ; c c, 

 colleterial glands ; s, probably the insertion of the 

 spermatheca not here visible. The ovarian caeca in 

 the oviparous female are not so numerous as are the 

 pseudovaria of the viviparous female. Although only 

 six separate branches are visible in this figure, probably 

 eight, viz. four on each side, are the correct number; 

 at k the constriction of the apical caecum has com- 

 menced. Dissected in petroleum spirit. 40 diam. 



Fig. 4. — Ovarian caeca with part of the alimentary 

 canal of the pupae of Chermes abietis. The embryonic 

 masses forming the incipient eggs are green, and 

 show different conditions of maturity. In some caeca 

 the apical chamber is almost obliterated, but in all, the 

 glandular masses are floating in a colourless fluid. 



