POLYCLADS OF THE ATLANTIC COAST^ HYMAN 479 



diilar vaginal fold characteristic of the genus is present in only the 

 anterior vaginal wall in G. foridana. 



Distribution. — Florida to Massachusetts, common in the southern 

 part of the range. 



Habits. — Among sea^yeeds, quick, active, may swim to some extent. 



Remarks. — Pearse placed this species in the wrong family and 

 genus. In Pearse and in Pearse and Littler the species is called 

 Stylochoplana -florid ana.., and in Pearse and Walker the name Stylo- 

 choplaTia ocuJifera is used, apparently for the same species. As I 

 pointed out (Hyman, 1939a), Verrill saw a specimen of this species 

 at Quisset Harbor near Woods Hole and mistakenly identified it as 

 Imogine oculifera Girard. I therefore gave the animal a new name, 

 Gnesioceros verriUi^ but as Pearse's publication antedates mine, it is 

 necessary to alter the name to Gnesioceros floridana. 



PLANCTOPLANELLA, new genus 



Definition. — Planoceridae without true seminal vesicle ; interpolated 

 prostate with transverse chambers as in Gnesioceros ; cirrus sac with 

 thick muscular wall and vermiform cirrus papilla as in Planctoplatia; 

 Lang's vesicle absent. 



Type. — P. atlantica, new species. 



PLANCTOPLANELLA ATLANTICA, new species 

 FiGUKES 29, d; 30 



Material. — Four specimens in vial sent by U. S. National Museum, 

 serial sections made of sexual region of one of them. 



Form. — Egg-shaped (fig. 30, a), posterior end broadest, to 8.5 nmi. 

 long by 4 mm. wide (preserved) ; no evident tentacles, but their ab- 

 sence is not certain, as no suitable sections are available to determine 

 this point. 



Eyes. — Small, all of the same size, tentacular clusters not very dis- 

 tinct from cerebral groups; eyes loosely arranged, extending behind 

 and in front of the brain (fig. 29, d). 



Color. — Preserved specimens white, probably translucent in life. 



Digestive tract. — Phar3aix small, central, Avith a few folds (fig. 30, 

 a) ; intestine dendritic, anastomosed. 



Reproductive system. — Enlarged vasa deferentia along posterior 

 half of pharynx (fig. 30, a) have thin muscular coats, hence form 

 moderately developed accessory seminal vesicles. They enter sepa- 

 rately the anterior end of the prostate, so that a true seminal vesicle 

 is absent. Prostate (fig. 30, c) as in Gtiesioceros., elongate with trans- 

 verse glandular chambers and thick muscle coat. The chambers are 

 lined with eosinophilous gland cells borne on connective tissue parti- 



