OF CYLINDRICAL WORMS. 539 



prebends, in man, the three following genera: Filaria, Tri- 

 chocephahiSj and flscaris. 



856. The ascaris has the body round, tapering at the two 

 ends, the head furnished with three tubercles; the penis of the 

 male is pointed and bifid. Two species are found in the hu- 

 man body. 



The #. lumbricoideS) the head of which is naked, the body 

 several inches long (3 to 12), marked with two opposite fur- 

 rows, the tail a little obtuse, inhabits the small intestines. The 

 #. vermicular 'is , Oxyuris vermicularis, (Bremser), has the 

 head obtuse, furnished with a vesicular membrane on each 

 side; its body is a little thickened anteriorly; the tail of the 

 male is flexed and obtuse; that of the female is straight and 

 flattened. It inhabits the large intestines, especially the rec- 

 tum. 



857. The trichocephalus has the anterior part of the body 

 capillary, the rest suddenly a little more voluminous; the 

 mouth orbicular; the penis simple, and sheathed. 



The T. dispar is found in man: it is unarmed; its capillary 

 part is very long, its head pointed; the body of the female is 

 nearly straight; that of the male is spiral; the sheath of the 

 penis is ovoid. This worm, observed by Morgagni, Wris- 

 berg, Roedorer, and Wagler, is very common. It inhabits the 

 large intestines, and especially the coecum. 



858. The filaria has the body elongated and nearly equal, 

 the mouth orbicular; the penis of the male is pointed and 

 simple. 



The F. medinensis, which is very long, which has the head 

 slender, the tail flattened and flexed in the male, semi-cylin- 

 drical, pointed, and curved in the female, is met with in the 

 human species, but only between the tropics. It inhabits 

 the subcutaneous cellular tissue, especially that of the feet. 

 It was thought formerly to be an exterior penetrating worm; it 

 appears to be really an entozoary one. The F. of the bronchia?, 

 F. bronchialis, is a doubtful species, observed and described 

 by Treutler, under the name of Hamularia lymphatica. 



859. The strongylus gigas has been numbered among the 

 worms which inhabit the human body, because Ruysch says 



