504 



8. DICnANOTAENIA FURCIGKRA (Riidnlphl, 1819) Stiles, 1896. 



(IM'J, ■•'!'. iiiluuala Batsch" ol' Kuihilphi; lM:i, 'J. iiirriKeia 

 Rudolphi ex Nitzseh, MS.; 1845, T. rhomiboidea Duj.; 1893, 

 Dicranotaenia rhomboidea (Dujardin, 1845) Radlliet.) 



( ? 1779, Taenia lineata Bloch; ? 1786, T. trilineata Batch; ? 

 1790, T. Anatis j8 lineata Gmelin; ? 1802, T. longirostris Frolioh 

 [nee Rud., 1819] ? 1803, Halysi.s trilineata (Batseh, 1786) Zeder; 

 ? 1858, T. conlca Molin.) 



[PI. Ill, figs. 31-34 (35-36).-] 



Diagnosis: 100"'m to 35""" long by 0.5 to 1mm broad. Head 

 0.46mm to 0.52mni^ ihomboidal, or prolonged anteriorily in a tube 

 containing a thick ovoide, oblong, rostellum 0.22mm to 0.25min 

 long, armed with a single crown of hooks 65 fi to Q6 /i (Dujardin). 

 48 /u to 58 /U (Krabbe) long. Suckers 0.18mm in diameter. Seg- 

 ments trapezoidal, 2 to 3 times longer than broad. Genital 

 pores unilateral. Penis 9.7 fi broad, smooth. Eimbryo 36 ft; 

 hooks of embryo 14 /i (Krabbe), 16 /« to 17 // (Dujardin). De- 

 velopment not known. 



Hosts: Mallard ducks (Anas boschas) by Dujardin, Nitzch, 

 Krabbe, Frils; Pochard (Aythya ferina); is erroneously stated 

 to have been found in domestic ducks, according to Railliet. 

 See also hosts for T. conica, T. lineata, and T. trilineata, in 

 chart at end of text, taken from von Linstow, 1878, and others. 



Geographical distribution: France (by Dujardin), Italy (by 

 de Ninni), Iceland (Krabbe), Schleswig (Friis). Epidemics, 

 none recorded. 



The early history of this worm is buried under indefinite and 

 incomplete statements upon superficially studied material. 

 We can, however, trace the species with certainty as far back 

 as Rudolphi, 1819, p. 528. Nitzseh collected some worms from 

 the Mallard in 1816, and sent them to Rudolphi. evidently under 

 the MS. label Taenia furcigera. Rudolphi determined the 

 worms as T. trilineata Batseh, 1786, which according to Krabbe 

 (1869, p. 315), (Batsch's original not at my disposal), is a name 

 Batseh introduced for Bloch's T. lineata of 1779. Krabb? after- 

 ward examined Nitzsch's specimens, and states (1869. p. 315) 

 that they are identical with T. rhomboidea Dujardin. 1845. I 

 adopt Nitzsch's name for the reasons given in the footnote. i 



1A very delicate point of nomenclature is involved in this 

 ease, and one which has been entirely overlooked by helmin- 

 thologists. In the first place, the name trilineata should be 

 .suppressed because (Krabbe, 1869, p. .315) it wa'? originally in- 

 tended for a species (i. e., T lineata from A. penelope. A. circia. 

 Dafila acuta) already named and figured. Accordingly, tri- 



