CESTODA 



107 



the largest human cestode at present known, attaining a length 

 of more than twenty -five feet, and sometimes measuring nearly 

 an inch in breadth ; the so-called head ^" in width, bluntly 

 pointed at the tip, much elongated or club- 

 shaped, slightly flattened from behind for- 

 wards, and furnished with two laterally disposed 

 slit-like fossae or grooves, but destitute of any 

 armature : anterior or sexually-immature seg- 

 ments of the body extremely narrow, enlarging 

 in a very gradual manner from above down- 

 wards ; joints of the lower half of the body 

 gradually decreasing in width, but enlarging 

 in depth; sexually-mature segments usually 

 about J of an inch in depth, but those near 

 the caudal extremity frequently J" ', and quad- 

 rate in form ; body flattened, but not so uni- 

 formly as obtains in the ordinary tapeworms, 

 being rather thicker near the central line ; 

 total number of joints estimated at nearly 

 4000, the first sexually-mature ones being 

 somewhere about the six hundredth from the 

 head ; reproductive orifices at the central line, 

 towards the upper part of the segment at the 

 ventral aspect, the vaginal aperture being 

 immediately below the male outlet, and both 

 openings surrounded bypapillaeform eminences; 

 uterus consisting of a single tube, often seen 

 regularly folded upon itself, forming an opaque, 

 conspicuous, centrally-situated rosette; eggs 

 oval, measuring ^" in length by - f in breadth, / 



having three shell-coverings, and a lid-like FIG. 25. Head and nerk 



, , . -i /i i of Bothriocephalus latus. 



operculum at one end, as occurs in the fluke- , Front view, ihe 



WOrmS. OwinST tO the dark Color of the eSTSf the head as seen frointhe 

 , ,, ., . ,., side. After Enoch. 



shells, the uterine rosette is readily seen by 



the naked eye as a conspicuous deep brown spot at the centre 



of each successive segment. 



The source and development of this parasite are points of 

 considerable interest. The eggs are of comparatively large size, 

 and after expulsion and immersion in water they give passage 

 to beautifully ciliated embryos, which latter produce larvae 

 furnished with a boring apparatus. These larvae resemble the 

 six-hooked embryos/ of other tapeworms. In what animals the 



