NEMATODA 



225 



Fig. 358 

 Ascaris cants. 

 Cross section 

 showing fins 

 (from Braun). 



A. equonim Goeze (A. megalocephala Cloquet). Maw worm. Length 

 15 to 37 cm. ; thickness 8 to 12 mm. ; eggs spherical, .1 mm. in diameter : 

 in the small intestine of the horse, often in large num- 

 bers, when it is a dangerous parasite. 



A. canis (Werner) (A. mystax Zeder) (Fig. 358). 

 Male 6 cm. long, 1 mm. thick; female 18 cm. long; a 

 pair of fin-like projections on the sides of the head; 

 eggs (Fig. 345, D) almost spherical, about .07 mm. in 

 diameter: in the intestine of cats and dogs, usually 

 common, occasionally in man; development direct. 



2. OXYURIS Rudolphi. Small worms in which the 3 lips are more 

 or less indistinct; oesophagus long, with 'a bulb followed by a dilated 

 portion; hinder end of male very short with but 1 spic- 

 ule; vulva in forward half; hinder end of female taper- 

 ing to a sharp point: about 15 species; in the large 

 intestine of vertebrates, also in certain insects. 



0. vermicularis (L.). Pin worm (Fig. 359). Female 

 10 mm. long; .6 mm. thick; male 4 mm. long; a dorsal 

 and a ventral cuticular projection on the head; egg 

 (Fig. 345, F) .05 mm. by .02 mm.: in the large intes- 

 tine, also occasionally in other parts of the digestive 

 tract of man, especially of children; often the indirect 

 cause of appendicitis; development direct, the eggs of 

 the females being taken in with drinking water or 

 directly from the hands. 



3. HETERAKIS Dujardin. Lips as in Ascaris; male 

 with a large sucker surrounded by 4 papillae before 

 the anus and 2 lateral thickenings; oral papillae small: 

 numerous species. 



H. vescularis Froehlich. Length 7 to 15 mm.; tail 

 of male with 5 preanal and 7 postanal papillae ; no teeth 

 in mouth : in the large intestine of chickens and ducks. 

 H. brevicauda (Zeder). Length 5 mm.; mouth surrounded by 10 

 papillae : in the intestine of frogs and toads. 



Fig. 359 



Oxyuris 



vermicularis 



(from Braun). 



A, female 



B, male. 



1, oesophagus 



2, vulva; 3, anus. 



CLASS 2. GORDIACEA * 



Hair worms. Long and very slender worms of the same diameter 

 throughout and never sharply pointed behind, which are sometimes found 



* See "The Gordiacea of Certain American Collections," by T. H. Montgomery, 

 Bull. Mus. Comp. Zool., Harvard, Vol. 32, 1898. Ibid., by the same, Pt. 2, Proc. 

 Cal. Acad. C. Sci., 3rd Ser., Vol. 1, 1898. "Synopsis of the Gordiacea," by the same, 

 Am. Nat, Vol. 33, p. 647, 1899. 



