DESCRIPTION OF PLATE G. 



Reproductive organs of tfie Male Aphis. 



Fig. 1. — Profile view of the last abdominal rings of 

 the male of Drepanosiphum platanoides with the ex- 

 serted penis : «, anus situated immediately under the 

 cauda ; r, the copulative armature and part of the 

 horny ring used to secure contact with the female ; 

 o o, opercula closing the genital opening ; k, the outer 

 sheath of the penis, which forms the inner lining when 

 the organ is retracted within the body-cavity ; //, 

 folds of the inner tube, which conversely becomes the 

 outer lining on retraction ; m, meatus penis, and part 

 of the ejaculatory canal ; s, seminal and muciparous 

 ducts. The walls of the inner tube of the penis are 

 more voluminous than the outer, and these folds (ff) 

 are obliterated when the organ is turned inside out. 



Fig. 2. — The same organs represented in plan, and 

 seen in situ before their protrusion, with the secretory 

 glands attached. The same lettering, as a rule, applies 

 to both these figures : c, the copulative sac ; j, the 

 ejaculatory tube ; d, deferent duct ; v, vesiculse semi- 

 nales ; g, muciparous glands with their ducts ; p, 

 testes or sperm-capsules ; g, genital opening. 



Fig. 3. — View of a testis with included sperm-cysts 

 in different conditions of maturity : a?, immature cyst 

 with sperm cells before they have developed filaments ; 

 y shows a cyst with the spermatozoa disposed in 

 bundles. 



Fig. 4. — A circular cyst more highly magnified, the 

 filaments of which (?/) are ranged in parallel order. 



These four preceding figures are after Balbiani. 



