356 T. B. ROSSETER ON THE ANATOMY OF DICRANOTJEN U CORONULA 



The specimens of this tape- worm used in my former investiga- 

 tions were found among the faeces of a Duck ; but those which 

 have been used in the preparation of this work were produced 

 by my feeding ducks with the Cysticercoids of this species, it 

 being one of four species of Cysticercoids with which I success- 

 fully infected ducks for the special purpose of producing the 

 mature worm (see " On Experimental Infection of Ducks 

 with Cysticercus coronula, etc.," Journ. Q. M. C, Ser. 2, vol. 6, 

 1897, p. 397). Of the thirteen known species of Tsenia, — not 

 including the new genus and species Echinocotyle Rosseteri 1891, 

 and the doubtful species Tcenia Krahhei Kowalewski, 1895, — 

 which make the Anserinse and the Anatinae their final hosts, 

 Dicranotcenia coromda is the most common, and in this respect 

 offers facilities for investigations and study ; but, owing to the 

 density and opacity of the parenchymatous tissue, and the 

 peculiar muscular structure of which the proglottides are com- 

 posed, it is a difficult subject to investigate so as to form an 

 accurate diagnosis of the position and formation of the male 

 and female generative organs. This difficulty was experienced 

 and has been commented on by such workers as Leuckart 

 and Moniez, in their investigations of the larger mammalian 

 tape-worms; thus it is easy to comprehend the difficulties to 

 be contended with in the preparation, staining, section-cutting, 

 and mounting so necessary for the investigation of these 

 comparatively small avian tape-worms. True, much good work 

 can be done by maceration and teasing, and I have obtained 

 a deal of information in this way ; but these methods, the latter 

 more especially, not only require a good supply of material but 

 a steady hand, a quick perceptive eye, and, what is above 

 all, a deal of patience. 



Dicranotcenia coronula is found in the lower portion of the 

 intestine, in close proximity to the rectum, and it is waste of 

 time to seek for it in the duodenum, the usual locality of tape- 

 worms, in the mucous-membrane of which they bury their 

 scolices, and attach themselves by their hooks and suckers. 



As a basis for a description of this worm we must take that 

 given by Dujardin. 



" Strobila long de 40 a 140 mm. (?), large de 1*5 mm. a 2 mm. 

 en arriere, insensiblement aminci, en avant, forme d'un tr^s 

 grand nombre d'articles tr^s courts ; tete largo de 0'20 mm. k 



