290 ENTOZOA. 



T. membranacea, Pallas ; Batscli. 

 T. humana inermis, Brera. 

 T. (a anneaux courts), Bonnet. 

 T. (sans epine), Andry. 



General and Specific Characters. — The largest cestode helmintli at present known to 

 infest tiie human body, attaining a length of more than twenty-five feet, and sometimes 

 measuring nearly an inch in breadth ; the so-called head J^" in width, bluntly pointed 

 at the tip, much elongated or club-shaped, slightly flattened from behind forwards, and 

 furnished with two laterally disposed slit-like fossae or grooves, but destitute of any arma- 

 ture : anterior or sexually-immature segments of the body extremely narrow, enlarging in 

 a very gradual manner from above downwards ; joints of the lower half of the body gradu- 

 ally decreasing in width, but enlarging in depth ; sexually -mature segments usually about 

 \ of an inch in depth, but those near the caudal extremity frequently i", and quadrate in 

 form ; body flattened, but not so uniformly 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 sis hundredth from the head (Leuckart) ; 

 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 by papillaeform eminences ; uterus consisting of a single tube, often 

 seen regularly folded upon itself, forming an opaque, conspicuous, centrally-disposed 

 rosette-like mass; eggs oval, measuring 3-^'' in length by ^" in breadth, having three 

 shell-coverings, and a lid-like operculura at one end, as occurs in the fluke-worms. 



The extreme rarity of the occurrence of this cestode in England 

 has hitherto prevented our paying much attention to the study of 

 its structural and other peculiarities ; consequently, our informa- 

 tion isj for the most part, due to Continental observers and especially 

 to Eschricht, Klichenmeister, Leuckart, and Knoch. Specimens, 

 indeed, exist in our museums, but in those few cases where they 

 have been obtained in this country, it has generally, if not invaria- 

 bly, happened that the individuals bearing them have come from 

 other quarters of Europe. Thanks to the liberality of Leuckart, 

 who has forwarded me various preparations, I have recently had 

 ample opportunity of confirming many of the anatomical details 

 which he has himself described ; and I may also mention that there 

 is a remarkably fine but incomplete specimen of this worm in the 

 Middlesex Hospital Museum. 



One of the most interesting points connected with the natural 

 history of the Bothriocephalus latus has reference to its distribution 



