PARASITES OF ANIMALS. 127 



wing-like membranous expansions on each side of the head 

 or anterior end of the body. The male grows to the length 

 of two and one-half inches ; the female sometimes becomes 

 four inches long and one-twelfth in diameter. 



This worm probably propagates its kind in a manner similar 

 to that of the two preceding species, and no doubt gains ad- 

 mittance to the human intestine, as well as to that of the cat, 

 by the medium of impure water and unclean vegetable food. 



Its effects and remedies are the same as those of the com- 

 mon round-worm. 



The Round-worm of the Hog (Ascaris suilla Dujardin). 



This very closely resembles the Ascarislumbricoides of man, 

 and probably has nearly the same habits. It differs chiefly in 

 the structure of the reproductive organs. The male spicules 

 are not so sharp, and the tubes of the uterus are much longer. 

 The eggs are smaller. It appears to be less common than 

 the Echinorhynchus gigas in the intestine of hogs, and prob- 

 ably produces less injurious effects. 



STEONGYLUS. 



The genus Strongylus includes slender, filiform worms, 

 mostly of small size, and often reddish in color. Several of 

 them live in the windpipe and bronchial tubes of various 

 animals, including sheep, deer, cattle, pigs, etc., and when 

 numerous may occasion the death of the animals that they 

 infest, by suffocation. 



The body generally tapers toward the head, and sometimes 

 in both directions. The mouth is small, situated at the end 

 of the small head, which is either simple or with lateral ex- 

 pansions. It is sometimes surrounded by small papilla, but is 

 often simple, and either round or triangular, but not enclosed 

 by a hard or chitinous organ, as in Sclerostoma, etc. The 

 oasophagus is enlarged, club-shaped, and muscular. 



The male has the posterior end of the body provided with 

 an expanded, often lobed pouch, or bursa, for adhering to the 

 female during copulation. The spicule is slender and filiform, 

 enclosed in a sheath. In the female the posterior end is 



