ECOXOMIC IMPOETAXCE OF XEMATODES . 329 



Aca7itliocheilonema j^erstans .—\({u\i foiius found 

 at base of the mesentery, especially around the pancreas. 

 Larval form, Mf. perstans, in blood. Tropical Africa, 

 British Guiana. 



Loa Zoa.— Found in various superficial connective 

 tissues, such as those of the conjunctiva, eyelid and other 

 parts, g'iving- rise to Calabar swellings. Larval stage is 

 Mf. diurna in the blood. Transmitted by Chnjsops fly. 

 Distribution: West Africa. 



Onchocerca iwlvulus.—Yonnd in subcutaneous 

 tumours. Occurs in West Africa. 



DRACUNCULIDAE. 



Dracunciihis iiicdinensis (" Guinea-worm "). — 

 Inhabits the subcutaneous connective tissue, and causes 

 superficial ulcers on the legs and feet. Larvae trans- 

 mitted by Cyclops, a fresh-water Ciiistacean. Endemic 

 in Tropical Africa, South America, Arabia, India. 



DIROFILARIIDAE. 



Diro filar ia inagalJiaesi.- — Found post-mortem in the 

 heart. Eeported from Rio de Janeiro. 



TRICHIXELLIDAE. 



Trichinella spiralis. — In the adult stage, this 

 parasite normally inhabits the small intestine of the 

 pig, wild boar, rat and man. The females are vivipar- 

 ous, and the larvae, deposited in the lymph spaces of 

 the intestines, are carried by the lymphatic and blood 

 streams to the muscular system in which they eventually 

 encyst. The encapsuled larvae, which may occur in the 

 muscles of man or pig", are liberated, and arrive at 

 maturity when introduced with food into another host. 

 This parasite, when present in large numbers, may be 

 fatal to man. Distribution almost universal. 



Trichuris trichiura (Trichocephalus dispar of 

 earlier writers). — 'The common '' whip-worm " of man. 

 It inhabits the caecum, vermiform appendix and colon, 

 and may cause anaemia and disturbances of the nervous 

 system. Distribution is apparently world-wide. 



DIOCTOPHYMIDAE. 



Dioctophymc rcnolc. — This parasite is usually 

 found in the pelvis of the kidney of the dog, wolf, fox 

 and horse, but is occasionally found in man, 



STRONGYLIDAE. 



Trichostrongylus instahilis and T. vifrinus are 

 occasionally found in man. 



Ternidens deminutus has been recorded from the 

 large intestine of natives in JSTyasaland. 



Oesophagostommn hrumpti was found in tumours 

 of the caecum and colon of an East African native. 



