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



gular confusion presented by the genus Bothriocephalic, 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 Acanthocephalce and Anacanthocephalce. 

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

 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 Tenioidea, 

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

 Bothriocephala. 



The Anacanthocephala are at present constituted of a single 

 family, embracing all the unarmed Bothriocephalce. 



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

 ment of the Cestoidea, for numerous investigations are still 

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

 development. 



CESTOIDEiE. 



Section I. Acanthocephalce. 



Family I. Tenioidece. 



Genera. Tenia . 



Halysis . 

 Trienophora 



Tenia Solium. 



H. genettae (Gerv.). 



T. nodosus. 



Family II. Bothrioidece. 



Genera. Acanthobothrium, n. g. Bothriocephaius bifurcatus. 



Echinobothrium, n. g. . E. typus. 



Dibothryorhynchus . D. lepidopii. 



Tetrarhynchus . . . Rhync. corollatus. 



Section II. Anacanthocephal^:. 



Family I. Bothriocephalidce. 



Genera. Phyllobothrium, n. g. . Bothriocephaius tumidulus. 



B. flos. 

 Fimbriaria ? . . . . Tenia malleus. 



Bothridium . . . 

 Bothriocephaius 



Schistocephalus 

 Cryptocephalus, n. g. 



B. megalocephalum. 



B. latus. 



B. punctatus. 



B. solidus. 



