NEMATOIDEA. 



41 



The male oxyuris is very small, and is usually 

 much rarer than the female. 



The species which is found in man is the Oxyuris 



Vermicularis, which ex- 

 ists in the lower part of 

 the large intestines, and 

 especially in the rectum. 



This entozoon is of a 

 whitish colour ; its head 

 presents two lateral 

 wing-like expansions of 

 the integument. 



The male is only 

 about one-third of the 

 size of the female ; its 

 tail is twisted spirally, 

 the extremity of it form- 

 ing a kind of sucker. 



Pig. 8.' 



Genus Ascaris. 



The ascarides are usually of a white or yellowish 

 colour, and of a cylindrical form, thinner in some 

 parts than in others ; their bodies are marked by 

 four longitudinal opaque lines, which are placed 

 opposite to each other ; the integument is striated 

 tranversely ; the head is furnished with three dis- 

 tinct convex, semi-globular, valves, very similar to 

 each other in appearance, of which one is placed 



^ Figure 8. — ^Female Oxyuris Vei-micularis. — 1. Four oxyuri- 

 des of the natural size. — 2. The cephalic end magnified ; the 

 oesophagus and stomach are shown. — 3. The caudal extremity 

 magnified. — 4. The head greatly enlarged ; a, the mouth furnished 

 with three lips ; h h, the lateral expansions of the integument. 



