REPORT OF THE BUREAU OP ANIMAL INDUSTRY. 171 



gall ducts are frequently completely distended by the teemse, which, 

 pack them so tightly that the parasites can not be -withdrawn by 

 pulling without breaking. Occasionally one, or at the most two, 

 may find their way into the pancreatic ducts, which they also dis- 

 tend. They get into these ducts when young and distend them as 

 they grow larger. 



A few disjointed segments may be found below the duodenum, but 

 no entire individuals. Nearly every sheep of a flock will be in- 

 fected. 



DISTRIBUTION. 



Tcznia fimbriata, Diesing, the fringed tape-worm, is at present the 

 most common parasite of the sheep of our Western plains, and causes 

 by far the greatest loss of any intestinal parasite in this country. 



As may be seen by inspection of the tables showing parasites found 

 in different post mortem observations, it has been identified in sheep 

 from Utah, Colorado, and Nebraska. Mr. Codweis, of Granger, 

 Colo., a former sheep owner in New Mexico, says that he has seen 

 them there. Mr. Samuel Collins, of Colorado Springs, Colo., who 

 has slaughtered sheep from California, Oregon, Utah, Nebraska, and 

 Colorado, says that all sheep from these States have them. Dr. Fa- 

 ville, of this Bureau, personally told me that he has seen them from 

 Oregon sheep and from sheep in New Mexico. Mr. Stewart's identi- 

 fication of Twnia plicata from Missouri sheep (National Live Stock 

 Journal, September, 1875), leads me to suspect its presence in that 

 State. When to these evidences of wide-spread distribution we add 

 those offered by the intermingling of Western sheep by parentage 

 and traffic, and by the opportunities for infection presented by the 

 nearly unrestricted communication of the ranges, we may believe 

 that this distribution is necessarily wide-spread. Its distribution at 

 present is from Oregon and Wyoming southward, and from Nebraska 

 and Missouri westward; or more accurately from the ninety -fifth de- 

 gree of west longitude westward, and from 45 north latitude south- 

 ward. It coincides with the distribution of the sheep in those parts; 

 and more especially with that of the descendants of the Mexican or 

 Spanish sheep with which nearly all of the larger ranches were origi- 

 nally stocked. The precise limit of its eastern distribution is un- 

 known, but I think is limited to those portions of Nebraska, Kansas, 

 and Missouri to which Colorado feeders have been sent prior to sell- 

 ing them to the Chicago markets. 



There are at present no facts at hand to show that the parasite 

 exists east of the Mississippi River. In two instances I found a num- 

 ber in sheep slaughtered in Washington, D. C., but these animals 

 were said to have come from Chicago, 111. 



LIFE HISTORY. 



All of the life history of this tsenia that is at present known has been 

 learned from post mortem dissections and microscopic investigation. 



The adults were found in yearlings and older sheep throughout 

 the year. No adults have yet been found in lambs less than ten 

 months old. The smallest stages of the immature taenia may be 

 found in all young sheep over ten months old. They are usually 

 most abundant in lambs, yearlings, and two-year olds. Although a 

 sheep may be infected with a number of tseniae of about the same 

 size, indicating an infection covering but little space of time, it is 



