434 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



Order POLYCLADIDA 

 Suborder Acotylea: Section Schematommata 



Family LEPTOPLANIDAE 

 Genus LEPTOPLANA Ehrenberg, 1831 (emend. Bock, 1913) 



LEPTOPLANA VESICULATA, new species 



Figure 51 



Material examined, — One specimen. 



Description. — Specimen 22 mm long, 11 mm wide. Of general 

 oval form (fig. 51, a), with ruffled edges, hence somewhat con- 

 tracted, with the typical appearance of a leptoplanid. No tentacles, 

 eyes in usual four clusters, paired rounded tentacular clustei"S of about 

 40-45 eyes, and paired elongated cerebral clusters of about 70-80 eyes. 

 Pharynx of typical ruffled leptoplanid type, central, encircled by the 

 uterus packed with eggs (fig. 51, a) ; mouth posterior to center but 

 contraction of the specimen may have altered its true position. 



Color. — Indeterminate, on account of long sojourn in alcohol, prob- 

 ably consisting of brown flecks dorsally. 



Reproducti've system. — ISIale apparatus shortly behind the pharynx, 

 female pore shortly behind the male pore; genital sucker present be- 

 tween male and female pores (fig. 51, h). Postpharyngeal portion of 

 specimen removed and sectioned serially; found to be in full sexual 

 maturity. Sexual apparatus cliaracteristic of the genus Leptoplana 

 (sensu stricto, Bock, 1913) but with a Lang's vesicle absent in the type 

 species of the genus. Sagittal semidiagrammatic view of copulatory 

 apparatus shown in figure 51, h. The male genital pore leads into 

 a vertical tubular cavity, the antrum masculinum, which, as in the 

 type species [Z. tremellaris (Miiller, 1774)], is provided with a fold, 

 termed by Bock the penis sheath. The portion of the antrum dorsal 

 to this fold is called by Bock the penis pocket. At its dorsal tenni- 

 nation it has the penis papilla, here very slightly developed, even 

 less so than in L. tremellans. From the penis the male duct con- 

 tinues dorsally as a tube considered by Bock to represent the granule 

 vesicle; no glands entering this tube are evident in the present speci- 

 men. At its upper end the granule vesicle (if such it be) has the 

 same lateral diverticulum found in L. tremellaris. The male duct 

 now turns sharply forward as a slightly expanded tube, then bends 

 dorsally again to enter the seminal vesicle. This is a highly muscular 

 rounded mass composed chiefly of circular fibers. It contains a tubular 

 cavity, slightly enlarged to a little rounded chamber where the com- 

 mon vas deferens enters from behind. The two vasa deferentia appear 



