220 NEMATHELMINTHES 



numerous small protuberances, irregularly distributed: beneath the con- 

 junctiva of the eye, in the eyelid, or in the subcutaneous tissue of other 

 parts of the body in man; on the west coast of Africa and occasionally 

 in America and Europe. 



F. medinensis (L.). Medina or Guinea worm. Length of female 

 2 m. or less; thickness 1.7 mm.; color white or yellowish; intestine 

 atrophied ; male not known : in the subcutaneous tissue of man, espe- 

 cially in the legs, also in domestic animals, producing a sore which 

 breaks to the outside, freeing the embryos; the young are found in 

 Cyclops and are probably conveyed with drinking water into the human 

 body; in Africa and other tropical countries, and supposed to be the 

 "burning fiery serpents" which troubled the children of Israel in the 

 desert. 



FAMILY 5. TEICHINELLIDAE. 



Elongated worms with the forward portion attenuated, often ex- 

 tremely so; mouth without papillae or teeth; oesophagus slender, without 

 bulb, and very long, in some cases being half as long as the body, and 

 situated beneath a very characteristic row of conspicuously large cells; 

 male with 1 spicule or none; female with but 1 ovary: 3 genera and 

 numerous species, all internal parasites. 



Key to the genera of Trichinellidae : 



! Forward portion very slender ; whip worms 1. TRICHURIS 



a a Forward portion not whip-like. 



\ Male without spicule 2. TRICHINELLA 



5 2 Male with spicule 3. TRICHOSOMA 



1. TRICHTTRIS Roederer (TrichocepJialus Goeze). 

 Body made up of 2 portions, a very slender forward 

 portion, containing the oesophagus, and a thick hinder 

 portion, containing the reproductive organs; hinder 

 end of male rolled up and with spicule; vulva at the 

 forward end of the thick portion: in the large intes- 

 tine, especially the caecum, of mammals; development 



direct, infection resulting from swallowing the eggs; 

 Fig. 352 

 Trichuris tricMura 1 species. 



A, female; B, male, T. trichiura* (L.) (TrichocepJialus dispar Ru- 



end imbedded in dolphi) (Fig. 352). Whip worm. Male 45 mm. long; 



mucous mem- female 50 mm. long; eggs (Fig. 345, E) ellipsoid, .05 



mm. long and .023 mm. thick: in man, cosmopolitan; 



perhaps the commonest intestinal parasite in man and often the indirect 



cause of appendicitis and typhoid fever. 



* See "A Statistical Study of the Prevalence of Intestinal Worms in Man," by 

 C. W. Stiles and P. E. Garrison, Bull. No. 28 of Hygienic Lab., 1906. 



