128 THEORY AND PRACTICE 



2. Strongyhis annatus (sclerostoma equi- 



num), found in the large intestines 

 of the horse. 



3. Oxynris cuvvula (commonly called pin 



worms), found in the intestines and 

 rectum of the horse. 



The ascaris megalocephala belongs to the family ascarides 

 of the order of nematodes. It is the largest species of its kind. 

 It is a large, round, yellowish white worm from 10-14 inches 

 long. It is oviparous and common in the small intestine of the 

 horse, ass and mule. When these worms are numerous enough 

 to cause an obstruction they may cause colic. 



The strongylus armatus is a blood sucking worm found in the 

 large intestine of the horse. It is from 1 to 2 inches long; body 

 gray or reddish brown and broad in its anterior part. The mouth 

 is provided with a ring of fine teeth by which it holds to the 

 mucous membrane. The larvae of the w^orm may be found in 

 aneurisms and may produce tumors as large as .a hazel nut in 

 the wall of the intestine (verminous cyst). 



The oxyuris curvula is the ordinary pin worm and is most 

 common in the rectum. It measures from 1 to 3 inches long; 

 curved in the anterior part of the body; the posterior half is 

 attenuated. Its mouth presents three great rounded lips. It be- 

 longs to the family oxyuridse of the order of nematodes. 



A scar id a e ( fajuily ) . 



Ascaris megalocephala (species), 

 Large round worm (common). 



Strongylidae ifaniUy). 



Strongylus armatus (sclerostoma 



equinum ) . 

 ^The armed worm. 

 Oxyiiridae (family). 



Oxyuris curvula (species). 

 Common pin worm. 



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