ANATOMY OF ACLESIA FREERI. 83 



mass (fig. 22, Plate IV) . Its walls are thinner, but considerably 

 firmer and stronger, than those of the albumen gland. The 

 internal cavity of the gland is large; it is partially divided into 

 an anterior and a posterior chamber by an inward projection 

 of the dorsal wall. The internal surfaces of the walls are folded 

 into low lamellae, which are approximately parallel to the axis 

 of the gland. The broad, short neck of the gland opens by a 

 large aperture into the ovarian side of the sperm-oviduct, just 

 back of the junction of the spermatocyst with the spermatic 

 duct (text figure 5) . 



The spermatocyst is a club-shaped sack, the narrow neck of 

 which is a direct continuation of the spermatic portion of the 

 sperm-oviduct (fig. 22, Plate IV; text figure 5). 



The common genital duct (sperm-oviduct) is divided into two 

 parallel tubes by a pair of longitudinal, internal folds arising 

 from the walls, whose edges are closely appressed. The ovi- 

 ducal portion is thicker-walled than the spermatic, the walls 

 being evidently glandular. Near the vulva, the sperm-oviduct 

 is twisted spirally. Two or more complete turns are made; 

 the spermatic portion of the duct thus comes to open into the 

 vulva upon the left side of the ovarian. There is a single 

 genital opening into the vulva, but the spermatic and ovarian 

 apertures are practically separated by the median septa previ- 

 ously mentioned. The seminal furrow enters the spermatic 

 duct, and can be traced along its wall nearly to the proximal 

 end. 



The globular spermatheca (Vesicle of Swammerdam) lies in 

 front and to the left of the genital aperture (fig. 23, Plate IV) . 

 Its slender duct passes backward and along the left side of the 

 vulva, crosses over the sperm-oviduct to the right side, and 

 turning forward enters a small diverticulum of the vulva upon 

 the right side. 



The penial aperture is found immediately under the right 

 tentacle. When the penis is indrawn, it lies in its sheath at 

 the right side of the pharynx. There is no prostate gland con- 

 nected with the organ. When extended the penis has the form 

 of a cylinder about 5 millimeters in diameter by from 14 to 

 18 millimeters long, terminating in a flattened expansion, the 

 prepuce (figs. 24 and 25, Plate IV) . The cylindrical base is 

 pigmented like the surrounding skin ; the prepuce is white. 

 The main flattened portion of the prepuce is about 9 by 7 

 millimeters in dimensions, nonmuscular, and apparently capable 

 of being considerably distended by vascularization. The distal 



