396 Univi rsity of California Publications in Zoology. I VoL - c 



reeeptaculum seminis by a small median portion. They are com- 

 posed of numerous rounded follicles, from which run collecting 

 tubules to empty into five main oviducts, one posterior, two 

 lateral and two anterior ducts. These lead into the reeeptaculum 

 ovorum, which is embedded in a mass of loose tissue in a depres- 

 sion on the anterior dorsal surface of the reeeptaculum seminis. 

 The reeeptaculum ovorum (rec. or., pi. 45, figs. 73, 75). is 

 about 3 mm. in its antero-posterior and its dorso-ventral diam- 

 eter and about (i mm. in transdiameter. These measurements are 

 the average for several sexually mature worms. 



The vitellaria are composed of loosely-grouped follicles, each 

 containing ten or fifteen cells, lying just within the inner trans- 

 verse musculature and outside the inner longitudinal. The fol- 

 licles are present throughout the body with the following excep- 

 tions : ( 1 ) dorsal and ventral to the uterus, that is, in the median 

 third of the body in the two middle quarters or more of its 

 length; (2) anterior to the posterior border of the acetabulum; 

 (3) posterior to the level of the ventral canal opening. 



The lateral folds are densely supplied with vitellarian fol- 

 licles, these forming the greater part of the folds. The ducts 

 of these yolk glands unite into four main lateral ducts, which 

 empty into a yolk reservoir, or "Endstiick. " which lies in the 

 dorsal depression of the reeeptaculum seminis above mentioned, 

 just posterior to the reeeptaculum ovorum. It gives off a single 

 efferent vitellary duet, which enters the afferent oviduct, as 

 described below, a short distance back of the entrance of the duct 

 connecting the efferent oviduct with the reeeptaculum seminis. 



The efferent yolk-ducts (pi. 39, fig. i'2, vit. d.), appear in 

 stained and cleared preparations as a dark brown anastomosing 

 network of delicate threads, spread over the reeeptaculum 

 seminis and the first three or four coils of the uterus, and con- 

 verging to the yolk-reservoir in the concavity of the reeep- 

 taculum. 



From the ventral surface of the reeeptaculum ovorum is 

 giveD off in the median line a single efferent duct (ef. ovd.) 

 which receives first a short thick-walled duct from the reeep- 

 taculum seminis (duct, son.) ; and then an efferent duct from 

 tlie yolk reservoir (ef. vit.d., pi. -45, figs. 71-7-4). This duct 



