THE BROAD TAPE-WORM OF SHEEP. 



TAENIA EXPANSA, Rlld. 

 Plates XIV aud XV. 



Tcenia expansa, the Broad Tape- worm, is one of the best known of the 

 internal parasites of sheep, because of its flatness, length, and large 

 size. In summer and fall it is quite abundant. The amount of pecun- 

 iary losses occasioned by its ravages depend upon the season and its 

 abundance in affected flocks. It was introduced into this country from 

 Europe along with the imported flocks which harbored it. Since then 

 it has been parasitical on our flocks from generation to generation. It 

 is now distributed from the wooded hillsides of New England to the 

 grazing lands of Georgia, over the fertile prairies of Ohio, Illinois, Iowa, 

 aud Nebraska, and the boundless prairies, basins, and mesas of Colorado, 

 Utah, California, and Oregon ; in short, over every sheep-grazing local- 

 ity in the United States. Ileported outbreaks from this vast extent of 

 country are comparatively few aud scattered, but are sufficient to warn 

 us that when the pastures become narrowetl, older, and overstocked, we 

 may expect the same trouble with this and other parasites as has been 

 experienced by sheep raisers through all time in the more densely pop- 

 ulated districts of other countries. 



Description. — The entire worm measures in length about 5 yards, and 

 in width from one-twenty-flfth of an inch at the head to a half or three- 

 quarters of an inch at the tail. Its thickness is from one-tenth to one- 

 twelfth of an inch. These dimensions vary greatly, depending on the 

 contracted condition of the worm when measured and on its state of pre- 

 serv^ation. Adult specimens taken from sheep may average less than 1 

 yards, or may slightly exceed 5 ; but they never, in this country at least, 

 attain that gigantic measurement of 100 feet ascribed to them by Eu- 

 ropean observers. The head is somewhat larger than the neck, and 

 measures one-twenty-fifth of an inch in width. It is smooth on the end 

 and has its four suckers directed anteriorly. Its neck, or that portion of 

 the worm immediately succeeding the head, which is uusegmeuted, is 

 shorter lacking. The body of the worm is apparently made up of a series 

 of very short but extremely wide joints, which vary in length and width 

 iu the successive portions of the body. The first rings of the tcenia are 

 very short and narrow; the others ape longer, but are always broadep 

 tUau long. Those seguaeuts wUicU are about two thirds the entire lengtU 

 23038 A P 8 U3 



