DESCRIPTION OF PLATE D.* 



Reproductive Organs of the Viviparous Aphis. 



Fig. 1. — Portion of the pseudovarium of Siphono- 

 phora pelargonii with some of its csecal chambers : 

 a a, terminal chambers : each of which has become 

 constricted in the midst : b, c, d s e, /, represent other 

 chambers with their embryos in progressive stages of 

 development. In f f the eyes have become differen- 

 tiated, and the body shows incipient segmentation. 

 The antennas, rostra, and legs are clearly marked. 

 The ovisacs are immediately connected with the 

 oviduct, one of which is indicated at h. The caudal 

 ends of the embryos are all turned towards the vulva or 

 genital opening. I could not clearly separate out the 

 colleterial glands of this specimen, but one probably is 

 shown as a blind sac near the base of the vagina at i. 

 /<•, the alimentary tube, charged with nutriment, and 

 ending in the rectum /. 



Only one branch of the oviduct is here represented, 

 and some only of the ovisacs are drawn. In some 

 species of Aphis the ovarian tubes number six on each 

 side ; and, as each tube may consist of six separate 

 chambers, full scope is afforded for the multiplication 

 of the insect. Dissected under weak syrup, January 

 6th. Mag. 34 diam. 



Fig. 2. — One of the pseudovigerous tubes of Sipho- 

 nophora rosce, much "magnified : a represents the apical 

 chamber, containing several ovarian glands, one of 

 which has been constricted off from the rest, and has 

 become the germinal vesicle with its germinal spot. 

 * Plates, A, B, and C, will be found in Vol. I. 



