593 



While it will be noticed that tliis rysticercoid is \eiy simi- 

 lar to Dicr. eoronula and that in all probability it represents 

 its larval stage, it must not be forgotten that the experimental 

 proof of the relationship of these organisms has not yet been 

 forthcoming, and fuirthermore. that even the adult form is 

 very superficially described. 



7 DICRANOTAENIA AEQUABILIS (Rudolph), 1810) Rallllet, 18S3 



(1810. Taenia aequabiiis Rudolph!.) 



[PI. Ill, figs. 29-30.1 



Diagnosis: IGOmm to SSOmm long, 3.2mm to 4.6mm broad. Head 

 subglobular; rostellum obovate, armed with a simple crown of 

 10 hooks 27 // to 32 /u long; suckers rather large, orbicular, 

 prominent. Neck very short. Anterior segments very short and 

 thin; following segments trapezoidal, much broader than long, 

 posterior angles acute, but becoming more rounded near the 

 posterior end. Genital pores unillateraJ. Development un- 

 known. 



Hosts: European swan (Olor cygnus); ? domesticated swan 

 (O. cygnus dom.); Widgeon (Anas penelope); European scaup 

 duck (Aythya marila). 



Geographical distribution: Pomerania (by Rudolphi and Crep- 

 lin); Schleswag (by Friis). Epidemics: None reported. 



Like the preceding species, this foi'iu has been seen 

 but a few times and is established entirely upon extcr 

 nal characters. ' 



Rudolphi collected it originally and described it in ISIO (pp. 

 l^fj-l.^.G) from wild swan. In 1819 (p. 15.5) he gives "Anas olor" 

 as a host. According to Diesing (1850, p. 527) Bremser found it 

 in Olor cygnus. Bellingham (1844, p. 320) quotes it for "Cyg- 

 nus ferus and Mareca penelope." Krabbe (1869, pp. 316-317) 

 examined the originals and figured the hooks; he cites in fur- 

 ther from Creplin's collection, and mentions that Friis also 

 found it. "Gervais and van Beneden. afterwards von Linstow. 

 cite it, probably erroneously, from the domesticated swan" 

 (Rallliet). Von IJnstow (1878. p. 158) records it for Fuligula 

 marila (—Aythya matila). Init does not give the collector. 



:is TT 



