44 THE ROUNDWORMS OF DOMESTIC SWINE. 



Family not determined. 1 



Genus Dioctophyme. Nematoda: Body cylindrical, mouth without 

 lips, surrounded by papillae. Male furnished with a filiform 

 spicule. Female with a single ovary. Vulva in the anterior part 



of the body Dictophyme visceralis. 



Family Ascaridae. Nematoda: One lip median, dorsal; two submedian, 

 ventral. Relatively thick forms. Males provided with two 

 spicules. Females with double ovary. 



Genus Ascaris. Ascaridae: Furnished with three strong lips, the 

 lateral sides of which are generally toothed. Males with two equal 

 or subequal spicules and numerous papillae anterior and posterior 

 of the anus. Vulva located anterior of the middle of the body. 

 Eggs globular or ellipsoidal, usually surrounded by an albu- 

 minous envelope. In process of segmentation at the time of ovi- 



position Ascaris suum. 



Order Acanthocephala. Nemathelminthes without mouth or digestive tube. 



Furnished with a protractile proboscis armed with hooks. 

 Family Gigantorhynchidae. Acanthocephala: Body large and annulated; 

 taeniaform. Hooks of the proboscis with two roots and covered 

 with a transparent layer of chitin. Lemnisci lengthened into the 

 form of rounded bags and having a central canal. 

 Genus Gigantorhynchus; with the characteristics of the family. 



Gigantorhynchus hirudinaceus. 



i Dioctophyme visceralis although commonly included in the family Strongylidse does not conform to all 

 the characteristics of this family. It more closely resembles the Filariidae as pointed out by Raillet and 

 Henry (1909a). Probably it should be placed in a family by itself, but the question is open to further study. 



