388 SYSTEMATIC ACCOUNT OF THE CESTODES. 



SYSTEMATIC ACCOUNT OF THE CESTODES. 



Budolphi, "Entozoorum s. verm, intest. hist, nat.," 1808-1810. 



Fr. S. Leuckart, " Zoologische Bruchstucke," Heft i., 1819. 



Dujardin, "Hist. nat. des Helminthea :" Paris, 1845. 



Van Beneden, "Vers Cestoides," Mim. Acad. Sci. SruaceUes, t. xxv., 1851. 



It is not only in regard to the life-history and development of the 

 Cestodes that our knowledge has increased in scope and complete- 

 ness ; the same must be said of our knowledge of the different forms 

 and their natural relationships. 



Apart from the bladder-worms and certain more isolated species, 

 such as Ligula, the older naturalists knew only a single genus of 

 tape-worms, Tcenia. It was, therefore, an important step when 

 Eudolphi not only increased the number of the unsegmented tape- 

 worms by the erection of different genera {Gary(yphyllcBus, Trieuspidaria), 

 but also separated a number of species from Tcenia on the ground of 

 the structure of the head (foveis duahus instead of osculis quatuar 

 sudoriis), and formed them into a special genus, Bothriocephalus. 

 Although Eudolphi himself, in his later writings, prepared the way 

 for the further breaking up of this family, by establishing a group of 

 Rhynchdbothrii (i.e., Tetrarhynchi grown into tape-worms), it remained 

 for long with its original content. This persisted, indeed, until van 

 Beneden made us acquainted with the manifold Cestode forms para- 

 sitic in rays and sharks, and was not only compelled by his ex- 

 tended knowledge to erect numerous new genera, but made, for the 

 first time, an attempt towards a natural division of the group, which 

 henceforth included also the bladder-worms. 



Van Beneden distinguished four families of tape-worms, distin- 

 guished according to the number and structure of their suckers : the 

 Tetraphylles, Diphylles, Fseudophylles (= Bothriocephali sensu stricto), 

 and Aphylles (Teniens). It seems doubtful whether the group Diphyl- 

 lidia, which is only represented by a single genus, Uchineibothrium 

 (Fig. 226, B), should be retained ; I should rather divide the Tetra- 

 phyllidia into Bhynchobothria and Phyllohotliria, so that the Cestodes 

 would then fall into the four groups — Bhynchobothria (Tetrarhynchi 

 Phyllohothria, Tceniadce, and Bothriocephali (or Dibothria). 



The Bhynchobothria (Fig. 226, A) have a large head with four long 

 proboscides and four large suckers, which often coalesce in pairs. 



The Phyllobothria have four — rarely two — large, moveable, and 

 often very complex suckers, sometimes furnished with spines anteriorly, 

 and sometimes ^'^^"^o^^^jj^^^ Microsoft® 



