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 Cestoidee into Acanthocephale and Anacanthocephale. 
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 Teniordee, 
the latter that of the Bothrioidee, which includes a portion of the 
Bothriocephale. 
The Anacanthocephale are at present constituted of a single 
family, embracing all the unarmed Bothriocephale. 
We present the following as the first sketch of an arrange- 
ment of the Cestoidee, for numerous investigations are still 
needed to acquaint us with all the genera at each epoch of their 
development. 
CESTOIDE. 
Section I. ACANTHOCEPHALS. 
Family I. Tenioidee. 
Genera. Tenia. . . . . . Tenia Solium. 
Halysis . . . ... 4H. genettse (Gerv:). 
Trienophora. . . . T. nodosus. 
Family Il. Bothrioidee. 
Genera. Acanthobothrium, n.g. Bothriocephalus bifurcatus. 
Echinobothrium, n. g.. E. typus. 
Dibothryorhynchus ._ D. lepidopii. 
Tetrarhynchus . . . Rhyne. corollatus. 
Section II. ANACANTHOCEPHALS. 
Family I. Bothriocephalide. 
Genera. Phyllobothrium, n. g.. Bothriocephalus tumidulus. 
B. flos. 
Fimbriaria? . . . . Tenia malleus. 
Bothridium . . . . B. megalocephalum. 
Bothriocephalus . .  B. latus. 
B. punctatus. 
Schistocephalus B. solidus. 
Cryptocephalus, n. g. 
