144 



NEMATHELMINTHES 



Ollulanus tricuspis Leuck., which in the adult state is found 

 in the cat, chiefly in the intestine but also in the bronchi and 

 other parts, gives rise to larvae which are of enormous si/ 

 compared with the parent ; these leave the body, and if eaten 

 by a mouse encyst in its muscles, and if the mouse be devoured 

 by a cat, they complete their life-cycle by becoming sexually 

 mature. 



The genus Syngamus infests the trachea and bronchi of birds 

 more rarely of mammals. The red- or forked-worm, Syngamus 

 trachealis Sieb., is common in poultry and 

 game birds, and causes the disease known 

 as gapes, which is especially common in 

 young birds, and often gives rise to exten- 

 sive loss. The peculiarity of this genus 

 is that the male is permanently attached 

 to the female, its genital bursa- being so 

 closely adherent to the opening of the 

 oviduct that two specimens cannot be 

 separated without tearing the tissues. The 

 ova are not laid, but escape from the body 

 with fully-formed embryos iu them, by the 

 decay or rupture of their parent's body. 

 They hatch in damp earth or water in 

 from one to six weeks according to the 

 temperature. When swallowed by a fowl 

 they develop into adults, which reproduce 

 eggs in less than three weeks. No second 

 host is needed, but the embryos remain 

 alive in the alimentary canal of earth- 

 worms, and these doubtless to some extent 

 serve to spread the disease. 



Fig. 70. Syngamus trache- 

 alis Sieb., natural size 

 and magnified lour dia- 

 meters. The small 6 is 

 permanently attached to 

 the female. (From War- 

 burton. 1 ) 



III. Family Trichotrachelidae. 



This family is characterised by the anterior end of the body 

 being produced into a long whip-like neck. The mouth is small 

 and devoid of papillae. The oesophagus is very long, and it 

 traverses a peculiar strand of cells. 



Genera : Trichocephalus, Trichina, Trichosoma, and others. 

 1 Joum. Roy. Agric. Soc. 3rd series, vol. iv. 1893. 





