224 NEMATHELMINTHES 



S. equinus Mull. The armed palisade worm. Male 20 to 30 mm. 

 long ; female 23 to 55 mm. long, 2 mm. thick ; body red or brown, straight 

 and rigid; mouth with small teeth; egg .09 by .05 mm.: common in the 

 cascum or colon of the horse, causing colic; the young worms live in 

 water and moist earth and pass directly in drinking water into the 

 horse; they are also found in the abdominal arteries where they cause 

 aneurisms. 



7. CUCULLANUS 0. F. Miiller. Small worms with 2 lateral chitinous 

 plates on the head and with rudimentary bursa; mouth ridged longi- 

 tudinally ; male with a spicule ; vulva in the middle of the body : several 

 species. 



C. elegans Zeder. Male 8 mm. long; female 13 mm. long; body 

 yellowish or reddish; mouth with 6 papillae: in the intestine of the 

 perch and other fish. 



FAMILY 7. ASCAEIDAE. 



Body often rather stout and large; mouth surrounded by 3 promi- 

 nent lips, 1 dorsal and 2 ventral; oesophagus with 1 or 2 bulbs; hinder 

 end of male spirally curved and usually 1 or 2 spicules project from the 

 anus: several hundred species, almost all intestinal parasites in 

 vertebrates. 



Key to the genera of Ascaridae here described: 



! Large nematodes with prominent lips 1. ASCABIS 



o 2 Small nematodes with usually small lips. 



5 X Male with a sucker before the anus 3. HETERAKIS 



5 2 No sucker present 2. OXYTJRIS 



1. ASCAEIS L. Large worms in which the 3 lips are set off by a 

 constriction, forming a distinct knob at the front end of the body; 

 oesophagus without distinct bulb; male with 2 

 equal spicules and numerous ventral caudal papil- 

 lae: several hundred species, which live in the 

 intestines of birds and mammals. 



A. lumbricoides L. Eelworm (Fig. 357). Male 



15 to 25 cm - lon s> 3 mm - thick ; female 20 to 40 



Cm ' lon ^ 5 mm ' thick 5 e ^ ( Fi ^ 345 > C ) b wn, 

 fr n o d n ; t S;d? ntral VieW f with roughened surface, about .06 mm. by .05 



mm.; body with the appearance of an earth 



worm: in the small intestine of man and domestic animals, sometimes in 

 considerable numbers, especially in children, when they are dangerous 

 parasites; occasionally found in the liver, trachea, and other organs; 

 development direct, the eggs pass out with the feces, and the young 

 larvae develop in water or moist earth ; infection is got in drinking water, 

 or from the ground or from the skin of raw fruits. 



