564 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8 



prostatic vesicle and the ejaculatory duct of the seminal vesicle meet 

 and unite in the proximal part of the penis papilla and the common 

 duct so formed extends along the center of the penis papilla to its tip. 

 The penis papilla is an elongated structure with a thick muscular 

 wall covered with an epithelium that is thickened at the penis tip 

 and proximally becomes continuous with the lining epithelium of the 

 rather spacious male antrum, which exits ventrally by a narrow tubu- 

 lar passage. Under the epithelium of the male antrum is found a 

 considerable muscular investment. 



The female apparatus is very curious, much reduced, and springing 

 from the roof of the male antrum, something quite unusual in poly- 

 clads. This condition could hardly result from contraction on pres- 

 ervation. The female antrum as it leaves the male antrum is a nar- 

 row tube encu'cled by a thick muscular sphincter. The parts of the 

 female tract are unfortunately poorly preserved in the sections. The 

 antrum widens to an ascending vagina that then descends as a tube 

 with a wall of cuboidal cells. This seems to make a curve and ascend 

 but preservation was poor here. There next comes an oval glandular 

 part of the vagina, definitely seen, entered by cement glands. A 

 narrowed tube leaves this and descends, then widening to a sac that 

 seems to receive two ducts; the connection with these ducts could 

 not be followed although very probably it is as shown in the figure. 

 These two ducts descend behind the male antrum and then curve 

 anteriorly. They seem to be the uteri and could be followed, although 

 not too clearly, to the rear ends of the egg-filled uteri shown in 

 figure 66. It is possible that the two ducts are the double Lang's ves- 

 icle characteristic of the genus Callioplana, but in that case the uteri 

 would enter the vagina beyond the glandular region and no indication 

 of ducts here could be found. 



Holotype: USNM 28686, one set of sagittal sections (one slide). 



Remarks: Since the female tract was unclear, it was difficult to 

 make a decision about this worm. If the two ducts discussed above 

 are Lang's vesicles rather than uteri, the specimen could be fitted into 

 the genus Callioplana, with which the male system is in accord al- 

 though the lack of tentacles and the characters of the female system 

 disagi'ee with the two known species of that genus: C. marginata 

 (Stimpson) (1857) and evelinae (Marcus) (1954). The matter cannot 

 be decided until better material is obtained. 



