600 



lowing Krabbe (1869, p. 300), stating that it was impossible to 

 recognize definitely what goose tapeworm was included under 

 the specific name fasciata by earlier authors, proposed to ap- 

 ply the name to a worm in geese provided with 8 hooks on the 

 rostellum. Authors have since Krabbe's time adopted his form 

 as fasciata. I retain this name provisionally, although it has 

 no right to stand. 



Mrazek (1890, 1891) records a cysticercoid from Cypris a^ilis 

 which he identifies as the larval stage of Taenia fasciata Ru- 

 dolphi. He evidently made no infections. 



12. DRBPANIDDTAENIA GRACILIS i[ ? Zeder. 1«0S] Krabbe. 186?) Rallliet, 



1892. 



(1869, Taenia gracilis Krabbe.) 



( ? 1782, Taenia collo longissimo Bloch; ? 1803 Halysis gracilis 

 Zeder; ? 1810, T. gracilis (Zeder) Rud.) 



[PI. VII, figs. 80-91; PI. VIII, figs. 92-99.-1 



Diagnosis: About 270mm long by 1.5-2mm broad. Head sub- 

 globular; rostellum cylindrical, obtuse, armed with a simple 

 crown of 8 hooks 77-80 fi long (95 H and even 103 // after Lonn- 

 berg). Neck very short. Anterior portion of body very thin 

 for a considerable length; anterior segments infundibuliform, 

 the following segments gradually becoming quadrate, genital 

 pores unilateral. Receptaculum seminis pyriform; penis un- 

 armed; genital sinus provided wath large spines. 



Development: Cercocystis Dr. gracilis in Candona rostrata by 

 Scott, in Cypris compressa Baird (Cypria ophthalmica Jurine) 

 and Cyclops viridls Fischer by Mrazek, in Cypria ophthalmica 

 by Moniez. 



Hosts: Tame duck (Anas boschas dom.); mallard duck (A. 

 boschas); widgeon (Anas penelope); tame goose (Anser anser 

 dom.); goosander (Merganser merganser); red-breasted mer- 

 ganser (Merganser serrator); common sheldrake (Tadorna ta- 

 doina). 



Geographical distribution: Denmark, Germany. No epi- 

 demics recorded. 



It is impossible to tell what worm was referred to 

 under the specific term gracilis before Krabbe's time; 

 the earlier descriptions may therefore be ignored for 

 the present, the names being accepted as unidentifiable 

 synonyms; it is impossible to show that the earlier 

 wonns were not identical witli Ktabbr's foi-m from 



