CHAPTER II. 



ENTOZOA. 



The internal parasites, or entozoa, are placed under 

 the branch Vermes. 



Vermes (vermis — a worm) is divided into three 

 classes, viz.: Annelida, Nemathelmintha, and Plat- 

 helmintha. 



Annelida (annulus — a ring) includes the order 

 Discophori. This order includes the family Gnath- 

 obdellidae. This family includes the genus Haemo= 

 pis, which infests the pharynx and mouth. 



Nemathelmintha (nema — thread; helminth — 

 worm) is divided into two orders, viz.: Nematoda 

 and Acanthocephala. 



Nematoda (thread-like) is divided into five fam- 

 ilies, viz.: Filaridae, Ascaridae, Oxyuridae, Strongy- 

 lidae and Trichotrachelidae. 



Filaridae (filum — a thread) include the genera 

 Spiroptera, Simondsia, and Filaria. They are 

 thread-like worms infesting various parts of the body. 



Ascaridae (askarizo — to move briskly) include 

 the genus Ascaris, which infests the small intestines. 



Oxyuridae (oxyo — pointed; oura — tail) include 

 the genus Oxyuris, which infests the posterior bowel. 



Strongylidae (strongylos — cylindrical) include 

 the genera Strongylus, Sclerostoma, Stephanurus, 

 Syngamus, Oesophagostoma and Uncinaria, which 

 infest the various parts of the body. 



Trichotrachelidae (trix— hair) include the genera 

 Trichocephalus and Trichina, which infest the in- 

 testinal tract. 



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