106 
the proximal portion of the latter. The vas deferens now runs 
laterad again and near the junction of the inner and middle thirds 
of the pouch is transformed into the cirrus which opens outwardly at 
the tip of the cirrus pouch through the common genital pore. The 
portion of the vas deferens within the cirrus pouch, including the 
cirrus, is supplied with longitudinal and circular muscle fibers of 
vaiwing degrees of development in different portions. The cirrus 
(figs. 117, 121) is armed with spines and is often seen evaginated 
through the genital pore. The distal end of the cirrus pouch may 
also be extruded for some distance through the pore (fig. 120). The 
occurrence of a loop in the yas deferens, in its course within the cirrus 
pouch, as described for Tlymenolepis Janceolata^ has been demon- 
strated, also, in a number of other tapeworms, in Ilyinenolepis fasciata 
Fig. 118. — Cirrus pouch and cirrus of H. lanceolata. Enlarged. (After Feuereisen, 1868a, pi. 10, fig. 9.) 
Fig. 119. — Isolated cirrus of H. lanceolata. Enlarged. (After Megnin, 1881, pi. 4, fig. 7.) 
Fig. 120. — Extruded cirrus and tip of cirrus pouch of H. lanceolata. Enlarged. (After Feuereisen, 
1868a, pi. 4, fig. 8.) 
Fig. 121. — Transverse section of proglottid of H. lanceolata, showing the cirrus pouch and vagina: 
c., cirrus; 1. m., longitudinal muscles; m. pf., muscle plates of cirrus pouch; niy., myoblasts; vag., 
vagina; r. def., vas deferens; ves. sent, ext., vesicula seminalis externa; res. sem. int., vesicula seminalis 
interna. Enlarged. (After Wolffhiigel, 1900b, p. 52, fig. 3.) 
(Krabbe) by Feuereisen (1868a), in ILymenoleins gracilis b}" Wolffhiigel 
(1900a), in Hymenolep)'is megalojjs by Ransom (1902), and apparently 
in Ilymenolepis sin uosa by Kowalewski (1895). 
Female organs. — The vagina {rag..^ figs. 115, llT, 121) begins at the 
genital pore as a tube about 7 y in diameter, lying ventral and some- 
what anterior with respect to the middle line of the cirrus pouch, and 
courses along the ventral side of the latter. The outer two-thirds of 
the portion in relation with the cirrus pouch (fig. 122), according to 
Wolffhiigel, ds lined by thick cuticula covered with fine spines, and is 
supplied with an inner layer of circular muscle fibers and an outer 
layer of longitudinal fibers. ^During its course inward from the 
genital pore the vagina increases gradually in diameter (to about 20/4), 
