12 



BULLETIN 69, UNITED STATES NATIONAL MUSEUM. 



With the exception of the cirrus pouch and the distal portion of 

 the vagina, the reproductive organs are all contained in the medullary 

 portion of the segment, as the portion within the inner longitudinal 

 muscle layer may be termed. The vas deferens and vagina pass 



between the dorsal and ventral ex- 

 cretory canals and dorsal of the 

 lateral longitudinal nerve. 



Blale reproductive organs. — The 

 testicles (fig. 3, t.) are of the usual 

 oval shape, elongated dorso-ven- 

 trall}^, measuring 60 to 120ju, in diam- 

 eter, in number about 24. They are 

 located in the lateral and posterior 

 portions of the segment, inside of 

 the inner layer of longitudinal 

 muscles, extending forward to the 

 anterior border of the segment on 

 the dextral side. On the sinistral 

 side of the segment the testicles do 

 not extend so far forward, the an- 

 terior third of the segment on this side being occupied by the vas 

 deferens and seminal receptacle. 



In segments in which the female glands are at the height of their 

 development the testicles in the middle third of the segment are 



IQo. 



Fig. 2. — Davainea ehynchota: 

 Hooks. (a) Large hook from 



EOSTELLUM. (&) SMALL HOOK 

 FROM EOSTELLUM. (C) HOOK FROM 

 SUCKER. 



V. ,def . 

 sem. recept. / 



d»ex. — K- 



lOQtt. 



Pig. 3. — Davainea rhynchota : Sexually mature segment, horizontal section, e. p.. 

 Cirrus pouch, d. ex.. Dorsal excretory vessel, ov.. Ovary, sem. recept.. Seminal 

 receptacle, t.. Testicles, v. def., Vas defeeens. y. g.. Yolk gland. 



crowded toward the sides and are then disposed in two groups, one in 

 each lateral third of the medullary portion of the segment. In a 

 segm-cnt containing 22 testicles, 9 were located on the left-hand 

 (pore) side of the segment and 13 on the right-hand side. The vasa 

 efferentia unite near the middle of the segment, toward the dorsal 



