((02 



650 segments; nimilier of segrnients in longest worms probably 

 reaches 2.000. Head with a simple crown o£ 10 hooks 65 /i-7i 

 u long. Neck long. Fully matured segments half as thick as 

 broad. Genital pores unilateral; copulation begins with about 

 the five hundredth segment, uterus appears ca. 70 segments 

 later. Male organs: Testicles 3 in number, one on pore side, 

 two on aljorose side of segment; cirrus pouch dorsal of vagina, 

 elongate, extending to or slightly beyond the longitudinal 

 canals, and possessing vesicula seminalis in its proximal por- 

 tion; vas deferens swollen to an elongate vesicula seminalis 

 near the pore-side testicle. Female organs: Vagina slightly 

 longer than cirrus pouch, swelling into an enormous recepta- 

 culum seminis ventral of pore-side testicle; ovary large, about 

 in median line; vitellogene gland distal of ovary; shell gland 

 very small, dorso^roximal of vitellogene gland; uterus trans- 

 \erse, extending beyond longitudinal canals into the lateral 

 field. Ova very characteristic; elongate 195 /i-ns /i by 90 fi 

 with 3 shells; external shell thin and transparent, inner bhell 

 slightly constricted at lateral borders of the oncosphere; on- 

 cosphere elongate. 50 ft-GO f, hooks 10 ft-ll ft Dorsal canal 

 small, dorsal of ventral canal; genital canals pass dorsally 

 of dorsal and ventral canals. 



Larval stage: Cj^sticercoid develops in small mussel crabs 

 (Cypris incongruens Ramd.; Cypris ovata; Cypris compressa), 

 and consists of three portions: (1) Pcolex with (a) armed ros- 

 tellum and 2 rostellum sacs, (b) fou^r suckers provided with very 

 minute cuticular booklets (Schmidt), and (c) long, narrow neck 

 provided with 30-40 calcareous corpuscles; (2) a hoHow cyst or 

 sac, composed of three layers; (3) a long, thin tail, in which the 

 6 hooks of the oncosphere are visible. The excretory system 

 can be traced from the suckers to the end of the tail, where 

 it ends in a terminal vesicle. Extended, the entire body may 

 measure ea. 2mni, the tail being 3% to 4 times as long as the 

 cyst. The scolex is contracted into the cyst, which then meas- 

 ures 0.19nini to 0.20mm by 0.21mm to 0.2.')mm, tail 0.7mm to O.Smm. 



Ho.st: Domesticated duck (Anas boschas dom.); mallard (A. 

 boschas); pintail (Dafila acuta). 



Geographical distribution: Pomerania. by Creplin; Zealand 

 (Denmark), by Gad and Krabbe; Schlesiwig, by Friis; France, 

 by Moniez; Germany, by Schmidt. No e^pidemics recorded. 



Krabbe (1863, pp. 2S7-2SS) found some specimens in Creplin's 

 collection under the label Taenia larvis Bloch. collected from 

 tame ducks. These worms agreed with others of Creplin's 

 oollertion labeled sinuosa. from the same host, and with a third 

 lot of worms from Gurlfs collection labeled "Taenia porposa? 



