46 M. Van Beneden on a new genus of Cestoid Worm. 



gular confusion presented by the genus Bothriocephalus, and with 

 the necessity of another arrangement of Cestoid worms. 



The primary character to be adopted is taken from the pre- 

 sence or absence of hooks on the head, according to which we 

 divide the Cestoidece into Acanthocephdloi and Anacanthocephola. 

 The first, the more numerous, forms two very natural famihes, 

 one of which has a circle of hooks with four surrounding sucking- 

 discs, whilst the second possesses from two to four extremely 

 contractile lobes. The former family is that of the Tenioidece, 

 the latter that of the Bothrioidece, which includes a portion of the 

 Bothriocephalce. 



The Anacanthocephal(je are at present constituted of a single 

 family, embracing all the unarmed Bothriocejjhalcs. 



We present the following as the first sketch of an arrange- 

 ment of the Cestoidece, for numerous investigations are still 

 needed to acquaint us with all the genera at each epoch of their 

 development. 



CESTOIDE.E. 



Section I. Acanthocephal^<:. 



Family I. Tenioidece. 



Genera. Tenia Tenia Solium. 



Halysis H. genettae (Gerv.). 



Trienophora . . . . T. nodosus. 



Family II. BothrioidecB. 



Genera. Acanthobothrium, n. g. Bothriocephalns bifurcatus. 



Echinobothrium, n. g. . E. typus. 



Dibothr^'orhynchus . D. lepidopii. 



Tetrarhynchus . . . Rhync. corollatus. 



Section II. Anacanthocephal^e. 

 Family I. Bothriocephalidce. 



Genera. Phyllobothrium, n. g. . Bothriocephalus tumidulus. 



B. flo?. 

 Fimbriaria ? . . . . Tenia malleus. 

 Bothridium . . . . B. megalocephalum. 

 Bothriocephalus . . B. latus. 



B. punctatus. 

 Schistocephalus . . B. solidus. 

 Cryptocephalus, n. g. 



