148 HANDBOOK OF INVEKXEBRATE ZOOLOGY. 



through the vesicula seminis. i. Convoluted portion of vas deferens. 

 k. Vas deferens, k'. Its external opening in the fifteenth segment. 

 I. Ovaries in the thirteenth segment, m. Oviducts in " the fourteenth 

 segment, n. Enlarged setigerous glands in the eighth to thirteenth seg- 

 ments. 0. Ordinary external setigerous gland, o'. Ordinary internal 

 setigerous gland, p. Fibre connecting o and o'. q.- Segmental organ. 

 r. Its internal orifice, s. Its external orifice, shown in the thirteenth, 

 fourteenth and fifteenth segments, from which the other parts of the 

 glands have been removed. 



b. The ventral nerve chain. This is made up of: — 



(i.) Two •commissural cords, which run side by side, 

 and in contact, from the fourth to the last segment (Fig. 

 85, a; Fig. 87, a). 



(ii.) A double or bilateral ganglionic enlargement 

 (Fig. 87 ; 5, 6, 7), in each segment posterior to the third. 



(iii.) Two pairs of nerves (Figs. 85 and 87, 6), originate 

 in each ganglion, and pass to the muscles and viscera of 

 each segment. 



(iv.) A pair of nerves originate in the commissure an- 

 terior to the ganglion in each segment, and supply the 

 posterior face of the muscular partition (Figs. 85, 87, i). 



8. The segmental organs. 



In each segment except the first, second, and third, 

 there is a pair of segmental organs (Fig. 85, q), each of 

 which consists of 



a. A ciliated funnel (Figs. 85, r, and 87), which is 

 attached to the anterior face of each dissepiment near the 

 median line. It is a small, funnel-shaped pouch, with a 

 wide, ciliated opening, which communicates with the body 

 cavity. A much smaller tubular neck passes through the 

 partition, and thus connects the funnel with 



h. The glandular portion of the organ ; a long, greatly- 

 convoluted, delicate-walled tube (Fig. '^^, «, h, c, d), lined 

 with cilia, and richly supplied with blood-vessels, and 



