POLYCLADS OF THE ATLANTIC COAST HYMAN 481 



tions. The prostate continues directly into a chamber lined by an in- 

 definite tissue containing large cyanophilous masses (fig. 30, c), and 

 this is continuous with the cirrus sac. Latter has thick muscular wall 

 of radiating fibers and sinuous canallike lumen, which contains the 

 vermiform cirrus papilla, a long slender sinuous structure, which takes 

 its origin from the cyanophilous chamber just mentioned (fig. 29, a). 

 Cirrus papilla appears to have no cellular structure but to be a hollow 

 tube with a cuticularized wall. It is filled with eosinophilous gran- 

 ules, apparently coming from the prostate. Lumen of cirrus sac 

 lined by ordinary epithelium; no cuticularized structures, except the 

 cirrus papilla, could be found in male apparatus. 



Female pore separate from, shortly behind male pore; leads into 

 nonmuscular vagina greatly expanded into cement pouch, surrounded 

 by numerous cement glands (fig. 30, c). Anterior wall of cement 

 pouch has thickened sinuous epithelium, which receives most of cement 

 glands; from this region vagina continues dorsally as a narrowed 

 tube, which curves backward and receives uteri at its posterior end; 

 Lang's vcvsicle lacking. Uteri form enlarged canals alongside 

 pharynx, stuffed with eggs (fig. 30, a) . 



Distribution. — Taken in surface tow, 8 : 30-9 : 00 p. m., no date, 

 Sheepshead Shoal, off Beaufort, N. C. 



Habits. — Pelagic, presumably benthonic part of the time. 



Type. — Whole mount, sexual region as serial sections, U.S.N.M. No. 

 20534; other three specimens also mounted, deposited in U. S. National 

 Museum. 



Remarks. — The male apparatus of this genus combines the charac- 

 teristics of Gnesiocei'os and Planctoflana. The prostate with its 

 transverse chambers closely resembles that of Gnesioceros., and the 

 thick- walled cirrus sac with its canallike lumen containing a vermiform 

 cirrus papilla suggests Planctoplana. In Planctoplana.^ according to 

 Graff (1892), the cirrus paj^illa ("penis") has the usual histological 

 structure but is covered and lined by a cuticularized ("chitinized") 

 layer ; in Planet o pi aneUa the cirrus papilla seems to consist merely of 

 a cuticularized tube. Unlike other genera of the Planoceridae, 

 Planctoplanella is devoid of any armature of either the male or female 

 apparatus, unless the cirrus papilla be considered as such. The pow- 

 erful musculature of the cirrus sac indicates that this structure everts 

 in copulation, bringing the cirrus papilla to the exterior. 



Family ENANTIIDAE Graff, 1890 



Definition. — Schematommata with tubular pharynx in anterior part 

 of body, dii-ected forward; tentacles absent; body margin with cuticu- 

 lar spines ; copulatory complex immediately behind pharynx ; one or 

 two pairs of laterally extending uteri ; Lang's vesicle present. 



