236 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.40. 



of the penultimate with the caudal fifth of the body length. The 

 ceca are narrowest at the esophageal ends; their diameter increases 

 slightly in the direction of their cecal extremities. The oral sucker, 

 prepharynx, pharynx, and esophagus are lined with a cuticular layer; 

 the intestinal lumen is lined by a layer of large cubical epithelial cells. 



Genital system — Male organs. — The testes are in the intercecal area 

 in a zone slightly preequatorial. They are placed one to the right 

 and the other to the left of the median sagittal plane, near the mesial 

 or mesio-ventral aspect of the corresponding gut, but not abutting 

 the field of the latter, although in press preparations they may appear 

 to do so (as for instance in fig. 1 drawn from a press preparation) . The 

 testicular zones overlap more or less, but do not coincide, and their 

 fields are separate. The cephalically placed testis may belong to the 

 right or to the left side; in four of seven specimens studied the right 

 testis is in advance, in three it is the left. The testes are irregularly 

 globular in form, without surface indentations, approximately equal 

 in size, and measure about 0.195 mm. in diameter. A relatively 

 stout-walled vas efferens springs from the cephalic aspect of each. 

 Each vas passes mesio-cephalad assuming a position close to the dorsal 

 aspect of the corresponding ramus of the excretory vesicle. The vas 

 of the side in which the ovary is placed passes in its course in close 

 relation first to the ventral aspect of the globular cecal end of Laurer's 

 canal, then close to the ventral aspect of the receptaculum se minis; 

 later it passes close to the mesial aspect of the ovary, between the lat- 

 ter and the shell gland. Cephalad of the shell gland, the vas tends 

 toward the axial region to meet and unite with its fellow at the base of 

 the cirrus pouch. The cirrus sac is an elongate cylindrical thin-walled 

 structure measuring about 0.525 mm. in length and about 0.105 mm. 

 in maximum diameter. It incloses a slightly coiled vesicula, a short 

 prostatica, and a protrusile cirrus. With the cirrus retracted the* 

 ductus ejaculatorius discharges into an atrium which also receives 

 the vagina. The pouch lies dorso-cephalad of the acetabulum, its 

 axis directed obliquely cephalo-ventrad. In press preparations (fig. 1) 

 the pouch appears to take a somewhat curved (crescentic) course 

 laterally of the acetabulum somewhat as described and pictured by 

 Looss x for StypModora solitaria; in sections, however, one finds that 

 the pouch, although submedian, is, as here described, dorso-cephalad, 

 not lateral of the acetabulum. The base of the pouch is in a plane 

 slightly cephalad of the caudal margin of the acetabulum. 



Female organs. — The ovary is a globular body, somewhat smaller 

 than the acetabulum and considerably smaller than the testes; it is 

 placed to one side of the median plane in a zone that abuts or slightly 

 overlaps the acetabular zone cephalically, and is separated to a vari- 

 able extent from the zone of the cephalically placed testis, caudally. 



i 1902, p. 506, fig. 24. 



