593 



While it will he noticed that this cysticercoid is very simi- 

 lar to Dicr. coronula 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 furthermore, that even the adult form is 

 very superficially described. 



7 DICRANOTAENIA AEQUABILIS (Rudolphl. 1810) Railllet. 18S3 



(isio. Taenia aeciualiilis Rudolphi, i 



[PI, III, figs. 29-30.1 



Diagnosis: 160'"m to 350mm long, 3.2mm to 4.6iiim broad. Head 

 subglobular; rostellum obovate, armed with a simple crown of 

 10 hooks 27 ^ to 32 /i 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 uniilateraJ. Development un- 

 known. 



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

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

 duck (Aythya marila). 



Geographical distribution: Pomerania (by Rudolph! and Crep- 

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



Like the pieceding .species, this form has been seen 

 1)11 f a few times anc] is established entirely upon extei-- 

 nal characters. 



Rudolphi collected it originally anrl described it in 1810 (piv 

 135-136) from wild swan. In 1819 (p. 155) he gives "Anas olor" 

 as a host. According to Diesing (1^0, p. 527) Bremser found it 

 in Olor cygnus. Bellingham (1S44, p. 320) quotes it for "Cyg- 

 nus ferus and Mareca penelope." Krabbe (18S9, pp. 316-317) 

 examined the originals and fi.gured 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" 

 (Railliet). Von Linstow (1878, p. 158) records it for Fuligula 

 marila f=Aythya marila). but does not give the collector. 



