8 TKK'I.M) I I'KUKI.I.AIv'IA lUnM INlllAN I'lliKT 



from station L 25. The two specimens from each station are olniously specifically identical 

 with each other; bnt at first the penis and penis bulb of the specimens from different stations 

 appeared to differ. .After some study, however, I decided that the difference was one of 

 degree of extension and have concluded tiiat all four specimens belong to one species. As 

 they came from stations rather widely separated, it may Ije considered that all the Polycclis in 

 the collection are of one species. 



The ovaries are a pair of small rounded compact masses in the usual anterior position. 

 No parovaria were found. The oviducts exit from their lateral surfaces. They could not 

 be traced very W'ell in any of the specimens but appear to run immediately to the medial side 

 of the ventral nerve cords. At the level of the penis bulb they curve dorsally and above the 

 male atrium unite into a common oviduct (fig. 9, co) which immediately turns ventrally and 

 opens into the male atrium just anterior to the junction of the latter with the bursa stalk 

 (Plate I, fig. 7, and Plate II, fig. 3, co). This arrangement of course obtains throughout the 

 genus Polycelis. The oviducts do not embrace the bursa stalk since they unite anterior to it 

 around the sides of the penis bulb. A few eosinophilous shell glands occur around the point 

 of union of the oviducts. The yolk glands have the usual appearance and occur as masses of 

 large granular cells lying between the intestinal diverticula from the level of the ovaries to the 

 posterior end of the body. In one of the K 78 specimens they are exceedingly numerous and 

 conspicuous. Presumably the yolk glands behind the copulatory apparatus must connect with 

 the oviducts by special yolk ducts. 



The testes occupy the position typical of the genus Polycelis. They extend near the 

 ventral surface from the ovaries to the root of the pharynx in a double row, one row to each 

 side of the midline, lying between the bases of the intestinal diverticula. The testes could be 

 identified in all of the specimens sectioned consisting in asexual individuals of masses of 

 rounded cells in the resting state. They were also in this condition in the less mature L 25 

 specimen but were in active spermatogenesis in the other three sexual specimens in which also 

 the vasa deferentia contain sperm. 



The vasa deferentia form the usual tubular enlargements termed false seminal vesicles 

 easily seen along the rear part of the pharynx and sides of the bursa copulatrix. At the level 

 of the penis bulb they curve dorsally and enter the bulb separately one from each side 

 (Plate I, fig. 8, and Plate II, fig. 4, vd). They penetrate the wall of the penis bulb without 

 enlargement, each one opening on a papilla (Plate I, fig. 8, and Plate II, fig. 4) which pro- 

 jects into the cavity of the bulb from its sides. 



The penis bulb and penis differ so strikingly in the L 25 and the K 78 specimens that at 

 first I feared it would be necessary to distinguish two varieties of the species. However, I 

 finally concluded that the differences rest entirely in the muscular state of these parts. In 

 the L 25 specimens (Plate I, fig. 7), the copulatory apparatus is withdrawn and in rela.Ka- 

 tion. There is a large hollow penis bulb and a small conical penis. But in both of the K 78 

 worms, the bulb and penis are extruded (Plate II, fig. 3). The penis bulb is strongly con- 

 tracted into a muscular disk and its cavity has been projected into the penis. The latter 

 organ has thus incorporated the penis bulb and appears as a large muscular elongated organ 

 with a considerable cavity. If my conclusions are correct, these specimens furnish a striking 

 example of the rule of the bulb in the protrusion of the penis, its contraction converting 

 an apparently small weak penis into a large powerful elongated organ. Probably the penis 



