ZOOLOGY AND BOTAM. 



NOTICE OF SOME WORMS COLLECTED DURING PROFESSOR 

 HAYDEN'S EXPEDITION TO THE YELLOWSTONE RIVER IN 

 THE SUMMER OF 1871. 



By Prof. Joseph Leidy, of Philadelphia. 



Among other interesting observations and discoveries made incident- 

 ally to the chief ones of Prof. Hayden's recent geological explora- 

 tion of the country of the head- waters of the Yellowstone Eiver, he re- 

 ports that the Trout, which abounds in Yellowstone Lake, is greatly 

 infested with a species of tape-worm. A number of the worms were 

 collected by his assistant, 0. Carrington, and submitted to my exam- 

 ination ; but, unfortunately, the abundance of specimens placed in 

 alcohol so much diluted it as to cause the decomposition of nearly all. 



In Mr. Carrington's notes accompanying the specimens, he observes 

 that the smaller worms were contained in cysts adherent to the exterior 

 of the intestines, but the larger ones, up to six inches in length, were 

 found imbedded in the flesh. From five to fifty of the parasites were 

 found in a fish. When numerous they appeared to affect the health of 

 their host, and the fishes most infested could generally be told by their 

 duller colors, meagerness, and less activity, Mr. Carrington also states 

 that the trout is not infested in the same manner in the Yellowstone be- 

 low the upper falls. 



Among the specimens submitted to me were several 

 of the worms inclosed in oval sacs imbedded in frag- 

 ments of flesh. The sacs having remained unopened// 'J§ 

 preserved the contained parasite from the general de-^ 

 composition of the others, so as to enable me to ascer- 

 tain its character. It belongs to the genus Bothrio- 

 ceplialus, or rather to that section of it now named 

 I>ibothrium. Two species have long been known as 

 parasites of the Salmon and other members of the 

 same genus of fishes in Europe, but the tape- worm of 

 the Yellowstone trout appears to be a different one. 



Two of the best preserved specimens of the tape- worm 

 measure five inches in length by a line in width at the 

 broadest part. The head, almost a fourth of a line in 

 diameter, is obcordate, as represented in the magnified 

 figures subjoined. The two bothria, or suckers, are thick 

 and discoidal, placed back to back, obcordate in outline, 

 and directed with their broad and slightly depressed 

 surface toward the margin or narrower diameter of the body. The 

 body is flat, thick, with rounded margins, and is narrowly anuulated. 

 The annulations appear due to muscular bands, and number about ten 

 to the line. If other segments exist, independent of these annula- 

 tions, as a character of the worm, the condition of the sipecimens does 



