48 

 ovary, 



BULLETIN 69, UNITED STATES NATIONAL MUSEUM, 



Although Cler 



Pig. 



lOOjLL. 



37. DiOECHIS AMERI- 

 CANA : Head. 



c makes no reference to the presence of spines 

 on the suckers, this is a feature which is very 

 inconspicuous and may have been overlooked 

 by that author.® 



The differences mentioned seem to be in- 

 sufficient to warrant a separation of the two 

 forms, and the identification of the tape- 

 worms from Fulica americana as Diorchis 

 (LCUTninata^ accordingly, seems fully justi- 

 fiable. Fuhrmann (1908a, pp. 7, 81), how- 

 ever considers it improbable that the same 

 species should occur in birds so different as 

 Anserines and Ralliforms, and explains 

 Clerc's record of Diorchis acuminata in Fu- 

 lica as due to some error, possibly a mis- 

 take in labeling. A comj^arison of specimens 

 is needed to settle the question whether the 

 forms from ducks and Fulica are of the 

 same or different species. 



DIORCHIS AMERICANA, new species. 

 Figs. 37^2. 



This species, which seems heretofore to 

 have been undescribed, was found in company with Diorchis acumi- 

 nata in Fulica americana^ and is based on specimens 

 (from the collection of H. B. Ward, deposited in 

 the U. S. National Museum Helminthological Col- 

 lection, No. 7238), collected in Nebraska. 



External anatomy. 



bOjcb. 



The length of specimens whose posterior seg- 

 ments were gravid, but in which the eggs had evi- 

 dently not yet reached their full development, 

 was from 20 to 25 mm. and the maximum width 

 0.6 mm. The head (fig. 37) measures 160/x in 

 length by 250/x in wndth. The rostellum is similar 

 in shape to that of Diorchis acuminata but larger, 

 measuring Avhen fully extended 135/>i in length, 

 by 50/x in diameter at the base and 80/x in diam- 

 eter at the tip, armed with a crown of 10 hooks 

 (fig. 38) Q5fjL long, similar in form to those of Diorchis acuminata. 



« Since publishing his description of Diorchis acuminata Clerc has informed 

 Fuhrmann (1906b, p. 620) that he has observed that the suclvers may be armed. 



Fig. 38. — Diorchis 

 americana : hook 

 from rostellum. 



