166 ILLINOIS BIOLOGICAL MONOGRAPHS [454 



The cirrus-sac (Fig. 103), situated immediately behind the uterus sac or 

 lateral to its posterior end, is elliptical to slightly oval in outline, and measures 

 0.128 to 0.162mm. long, 0.087 to 0.116 wide and 0.098 to 0.116 deep. The 

 longitudinal axis is directed anterodorsally from the genital sinus and to the 

 right or left, according as it alternates with the uterus-sac. The proximal 

 one-third of the contents of the pouch consists of loose parenchymatous tissue 

 with a few muscle fibres svurrounding the ductus ejaculatorius, while the distal 

 two-thirds, that part which accommodates the cirrus proper, is supplied mostly 

 with muscles which actuate the latter. Large fibres proceed somewhat obli- 

 quely from the wall towards the proximal pole of the sac to become broken 

 up or frayed before they are attached to the cirrus tangentially, so as to give 

 the appearance in frontal sections of the latter being surrounded by a com- 

 paratively heavy layer of fine lightly staining circular fibres. A few of the 

 fibres closest to the cuticula of the cirrus were considered to be true circular 

 fibres; but no longitudinal fibres were seen. The wall of the cirrus-sac is from 

 2 to 3/i thick and is made up of very fine closely matted fibres, the direction 

 of which could not be determined with satisfaction. The sac lies freely in the 

 parenchyma of the region and is not connected by any special muscles to the 

 dorsal or ventral body-Vv^alls ; nor are the body muscles attached to it as in 

 some cestodes. The layers of the latter are simply pierced and the fibres turned 

 aside in evidently a passive manner. 



The opening of the vagina is close behind that of the cirrus at the bottom 

 of the secondary genital sinus, or as it has been called by Fuhrmann, "ductus 

 hermaphroditicus " (Fig. 103). From this point the duct courses ventropos- 

 teriorly in the mid-Hne and then parallel to the dorsal surface of the proglottis 

 imtU it reaches the ovarian isthmus, above which it makes a few turns and 

 quickly diminishes from 20/i in diameter half way along its course to lO/x. It 

 then dips farther down into the genital space, often enlarging slightly as it 

 does, and soon joins the oviduct at an enlargement of the latter situated a 

 short distance behind the oocapt. Throughout its length it is lined v/ith a 

 ragged or pseudociliated cuticula and surromided by radially arranged nuclei 

 connected with the cuticula by cytoplasmic strands like those described by 

 the writer for H. glolndiforme (1914a:105) and considered to be possibly ex- 

 truded nuclei of the original epithelium as well as the myoblastic nuclei of 

 circular fibres, a layer of which surrounds the duct. There is no vaginal sphinc- 

 ter. 



In his generic diagnosis Luhe states that the receptaculum seminis is small 

 and in his description of the family Ptychobothriidae (1902:327) says that when 

 present it is "in Gestalt eines kleinen Blindsackchens ausgebildet, welches 

 parallel neben dem Endabschnitte des Oviduktes Uegt and mit der Vagina 

 unmittelbar vor deren Vereinigung mit dem Ovidukt in Vergindung steht." 

 On the contrary it was found to be a comparatively large structure but very 

 difficult to orient in sections made in any direction. It is in the form of a 

 thin-walled sac about 60 by 20^, wrapped somewhat spirally around the dorsal 

 wall of the above-mentioned enlargement of the oviduct and opening by an 



