PHYLUM PLATYHELMINTHES 253 



ORDER 3. ASPIDOCOTYLEA. 



Endoparasitic Trematodes with direct development; adhesive 

 apparatus in the form of a large sucker, which is divided by 

 septa into compartments, and occupies nearly the entire ventral 

 surface. 



ORDER 4. TEMNOCEPHALEA. 



Trematodes with direct development, which live on the outer 

 surface or in the respiratory cavities of various animals e.g., Crusta- 

 ceans ; most non-parasitic as regards their nutrition, with organs 

 of adhesion in the form of a simple posterior sucker and a system 

 of anterior or marginal tentacle-like appendages. 



CLASS III. CESTODA. 



Endoparasitic Platyhelminthes without cilia and without di- 

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

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

 and an elongated compressed body consisting of a string of similar 

 proglottides, each containing a complete set of hermaphrodite 

 reproductive organs. 



ORDER 1. MONOZOA. 

 The body not divided into proglottides. 



ORDER 2. POLYZOA (MEROZOA). 

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



Systematic Position of the Examples. 



Planaria and Dendrocoelum are genera of the family Planaridcc 

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

 order Tricladida, differing from the other family, the Gcoplanidce 

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

 more dorso-ventrally compressed. 



The genus Fasciola, to which the Liver-Fluke belongs, is a 

 member of the family Distomidce of the Monogenetic Trematodes. 

 The Distomidce are characterised by the following features : They 

 have a cylindrical or more or less flattened body, always provided 

 with two suckers the anterior terminal or nearly so, the posterior 

 ventral and either terminal, or in a varying position on the ventral 

 surface. A pharynx may be present or absent. The intestine is 

 always forked, the limbs simple or branched. The genital pore is 



