Nematoids. Round Worms. 245 



Genus : Tricocephalus (trix hair, cephale head), Hair head, 

 Whipworm. lyong hair-like anterior part contains oeso- 

 phagus or moniliforni part of intestine ; short posterior 

 portion, suddenly greatly enlarged has intestine and 

 generative organs. Anus terminal. Spiculum single in 

 membranous sheath. Vulva at junction of thick and thin 

 portions of body. Ova, oblong with short neck at each 

 end. 



SECT. II. THREAD-WORMS. CHARACTERS. 



Body, long, delicate, thread-like ; mouth round or triangular. 



with or without papillae ; no salient lobes. Two unequal spiculae. 



Genus : Filaria, (filum thread) Thread-worms. Long, thin, 

 breadth to length as 1:80 or 1:500, cylindrical ; anus 

 terminal or nearly so. Main spiculum very long and 

 twisted, short spiculum twisted and obliquely striated. 

 Vulva close to head. Ova slightly elliptical. Oviparous 

 or viviparous. 



Genus: Spiroptera, (speira coil, pteron wing). Body cylin- 

 droid or uneven in thickness, mouth round, often ventricle 

 and cfficum. Anus in front of caudal extremity. Skin 

 with transverse striae. Tail spiral in male, straight in 

 female. Majority burrow in the cesophagean or gastric 

 mucosa. 



Genus : Dispharagus. Body long, slender ; mouth round ; 

 oesophagus in two parts, connected with a cylindroid ven- 

 triculus. Male usually in spiral. Two spicula. In 

 muco.sa of gullet or stomach. 



Genus: Ascaris. (Intestinal worm). Body very thick, cylin- 

 droid, narrowed toward each end ; mouth triangular, with 

 three labia having thick muscles ; no pharyngeal enlarge- 

 ment ; intestine straight ; males with 2 spicula ; vulva in 

 front of the middle of the body ; ova globular or nearly so. 

 Ivive in small intestine of mammals. 



Genus: Heterakis (dteros other, akis spiculum, point). Sepa- 

 rated from the Ascarides by Dugardin because the sec- 

 ond spiculum is very small or absent. Body like ascaris,, 

 labial lobes less pronounced, notches between more shal- 

 low ; pharynx separated from oesophagus by a horny 



