238 ZOOLOGY SECT. 



intestine consisting of a median anterior division and two lateral 

 posterior limbs which are provided with side branches. 



ORDER 3. RHABDOCCELIDA. 



Comparatively small Turbellaria, with the body usually elongate 

 and cylindrical or compressed : with simple, or nearly simple, sac- 

 like intestine: with or without yolk-glands: with one or two 

 ovaries and two or many testes. 



CLASS II. TREMATODA. 



Ecto- or endo-parasitic Platyhelminthes devoid of cilia, 1 or of a 

 cellular epidermis ; 2 with a well-developed digestive apparatus. 



ORDER 1. MONOGEXETICA. 

 Mostly ecto-parasitic Trematodes ; with direct development. 



ORDER 2. DIGEXETICA. 

 Endo-parasitic Trematodes with complicated life-history. 



CLASS III. CESTODA. ' 



1 .Is "? 



Endo-parasitic Platyhelminthes without cilia and without di- 

 gestive cavity, the animal consisting in most cases of a Bounded 

 head bearing organs of adhesion in the form of suckers and hooks, 

 j^nd an elongated compressed body consisting of a string ofsimilar 

 jproglottides, each containing a complete set of hermaphrodite 

 weproductiyje organs. 



ORDER 1. MOXOZOA. 

 The body not divided into proglottides. 



ORDER 2. POLYZOA. 

 The body consisting of head or scolex, and string of proglottides. 



Systematic Position of the Examples. 



Planar ia and Dendroccelum are genera of the family Planaridce, 

 or fresh- water Planarians, which is one of the two families of the 

 order Tricladida, differing from the other family, the Geoplanidce 

 or Land Planarians, mainly in having. the body less elongated and 

 more dorso-ventrally compressed. 



Distomum hepaticum is one of the very many species of the 

 genus Distomum, which is distinguished from the other three 



1 Except in certain species of Temnocephala. 



2 Except in the Temnoctphak<e and Actinodactyhlhi. 



