182 



PARASITOLOGY. 



TAENIA OVIS. 



Where Found.— Frequent in western part of the United 

 States. 



Description. — Adult worm 12 to 26 inches long. The ter- 

 minal segments are usually longer than broad. The head 

 IS provided with 4 oval suckers and a ros'tellum of from 24 

 to 36 hooklets. 



Life History. — Similar to that of the Taenia Marginata 

 except that the cystic form develops in the musculature, 

 both^ skeletal and heart. The cystic stage is called the 

 Cysticercus ovis. The cysts are oval in shape and average 

 about one-fourth inch in diameter. Each cyst contains one 

 head. 



Animal Infested.— Adu\t stage, intestines of the dog. 

 Cystic or larval stage the musculature of the sheep. 



TAPEWORMS OF DOG. 

 The tapeworms commonly found in the dog are 

 armed ; their life history is known. 



Taenia Marginata (Marginatus— margined). 

 Synonym. — Marginata tapeworm. Taenia Hydati- 

 gena. 



Distribution. — One of the common tapeworms of 

 the dog; the shepherd dogs are a common carrier of 

 Description. — The head is scarce- 

 ly wider than the neck and is pro- 

 vided with four sucker discs be- 

 tween which is located arostellum 

 of hooklets ; this rostellum is 

 arranged in a double circular form 

 and consists of from thirty to forty 

 hooklets. The neck is short ; the 

 segments as they develop from 

 the neck are shorter than broad. 

 As the distance from the head 

 grows greater the segments be- 

 come wider and longer; the mature 

 segments are nearly square ; the 

 ripe segments are slightly longer 



Fig-. 70 — 



Taenia Marginata. 



a, Head. 



b, Neck. 



c, Genital pore, 



d, Ripe segments. 



