16 T. B. ROSSETER ON DREPANIDOT^NIA VENUSTA. 



section shows that the walls are very thick, and that the lumen 

 is very narrow, being a trifle under 0*002 mm. in diameter. 

 The root also terminates in a fine straight point whose aperture 

 corresponds with that of the hook. When the tissue of the canal 

 in the ripened segments has become absorbed, this so-called root 

 of the cirrus is seen to be studded with small knobs, as if for the 

 more secure attachment of the neck of the looped vas deferens. 

 The cirrus itself is perfectly smooth, but the cirrus shield is 

 studded some distance down with rows of spinous prickles (Fig. 3, d). 

 Dr. Stiles, writing of Bertia Americana Leporis (Tapeworms of 

 hares and rabbits — Proceedings U.S. Xat. Mus. New York, 

 vol. xix., p. 168), thinks that these apparent rows of spines 

 are "wrinkles of the cuticle," and caused by the retraction of 

 the ciiTus. I do not think so, at least in this case, because not 

 only are they present when the cirrus is extruded, but they still 

 exist in the uterine segment even after absorption of the cirrus 

 itself, as in some segments undergoing absorption the cirrus has 

 preceded the pouch. I have not been able to trace definitely any 

 prostate glands, although at times I have fancied I could detect 

 a faintly glandular structure at the distal neck of the canal. 



The Female Orgaiis. — When the genital organs are fully developed 

 the genital papilla has become a stout, dense, muscular pro- 

 tuberance or boss, with a large orifice or cloaca. This papilla is 

 composed of longitudinal and circular muscles (Figs. 7, 8, and 9) ; 

 and a transverse section reveals the fact that these circular 

 muscles, which are secondary to the longitudinal ones, divide the 

 papilla into two distinct parts (Fig. 5, A — Ba). One set of circular 

 muscles suriounds the sinus genitalis, the other the distal portion 

 of the cirrus pouch. This papilla contains the vaginal canal, 

 which is anteo'ior to the cirrus pouch, and is joined to the latter 

 by the longitudinal muscular structure. The papilla is very 

 flexible, consequently the orifice assumes various shapes ; seen as 

 an oval, which apparently is its natural condition, it is 0-169 mm. 

 long by 0*102 mm. wide. The vagina. Fig. 10, /, lies compara- 

 tively deep down in the cloaca. The orifice of the canal is circular. 

 The canal is composed of bundles of stout longitudinal muscles ; 

 these are distinct from the long muscles of the cuticle of the 

 papilla, which in cross section give the vulva a stellate appear- 

 ance (Fig. 6, c). During coitus these muscular bundles contract, 

 and, in conjunction with the spines with which the canal is 



