POLYCLAD FLATWORMS — HYMAN 551 



cular coat, forming a bulbous vagina. This is slanted almost hori- 

 zontally forward. The vagina then narrows to an apparently sinuous 

 duct but parts here were not as clear as desirable. This sinuous 

 duct receives numerous cement glands; it gradually ascends and 

 finally curves posteriorly. After receiving from below the common 

 oviduct it descends posteriorly to terminate in a small pyriform 

 Lang's vesicle. 



The entire Eniwetok specimen (USNM 28670) was sectioned but 

 the sections proved unsatisfactory. As far as it could be discerned 

 the female apparatus resembled that of the Ifaluk specimen, having 

 a bulbous vagina followed by an apparently sinuous glandular section 

 of the vagina, but this again was not clear. The male apparatus could 

 not be followed satisfactorily and was deficient in the same area as 

 the Ifaluk specimen. One point was definite; the two gonopores 

 are close together and the male antrum ascends immediately in front 

 of the vagina. This may represent a geographic difference between 

 the two specimens; or the two specimens may represent different 

 species of Stylochoplana. The condition of the sexual apparatus of 

 the Eniwetok specimen does not justify describing it as a distinct 

 species, hence it is doubtfully assigned to Stylochoplana minuta. 



Differential diagnosis: Stylochoplana minuta is dintinguished 

 by the small size at sexual maturity, arrangement of the eyes in a 

 single row on each side, bulbous vagina, and sinuous course of the 

 glandular vagina. 



Holotype: USNM 28642. Anterior part of the Ifaluk specimen 

 as whole mount, postpharyngeal region as sagittal serial sections 

 (one slide). 



Notoplana micronesiana, new species 



Figures 2d,e', 3a 



Material: One specimen washed from algae in the intertidal 

 zone, Sept. 4, 1953, Ifaluk Atoll, near south end of Falarik lalet, 

 Sta. 23-E-l. 



General features: The worm is 18 mm. long, 3 mm. wide, of 

 elongated slender shape with rounded anterior end, blunt posterior 

 end (fig. 2d). Probably white in life, it was pale brown preserved. 

 The eyes (fig. 2e) are arranged in a continuous band on each side and 

 are not definitely delimited into cerebral and tentacular clusters. In 

 the cleared specimen scarcely anything could be seen of internal 

 structures. The pharynx was vaguely indicated as shown in figure 

 Id, but sexual structm'es were not detectable. However, the post- 

 pharyngeal region was removed and sectioned sagittally; it was found 

 to contain fully developed copulatory apparatuses. 



