603 



Anas boschas fera." llie laltt-r being in a bottle with otliers 

 which appeared to be T. rhomboidea. Friis found the same 

 worm in wild ducks in Schleswig, and Gad and Krabbe found 

 it in tame duclis in Zealand. The worm was found three 

 times in 100 tame ducks. Krabbe (18S2, p. 353 states that Pro- 

 fessor Reinhart found this same species in 1S71 in Anas acuta 

 [ — Daflla acuta! taken in Zealand. 



Mrazek (1891, pp. 110-113) describes a cysticercoid which he 

 found in Bohemia in Cypris incongruens and Cypris compressa 

 Baird (according to Moniez, 1891, Cypria ophthalmica); the larva 

 measured 0.40nini to 0.43""", and bore 10 hooks 65 H long; the 

 tail was very long; embryonic hooks measured 10 /*. Moniez 

 (1891, p. 26) states that he found the same larva in Cypris in- 

 congruens at Lille, France, and that the species T. anatina is 

 the most common tapeworm of domesticated ducks of that 

 country. 



It is to J. E. Schmidt (1SI)-1) that we owe our chief 

 knowledge of this worm and the experimental denidu 

 stratiou of its life history. Sdmiidt infected numer- 

 ous small 2.25""" to 2.75""'" fresh-water crustaceans 

 (<;ypris ovata) with the eggs of adult animals taken 

 from ducks, and followed the development in all its 

 stages. He found that the ova are eaten by Cypris; 

 the embryo escapes from its shells and passes into the 

 liody cavity of the intermediate host; here it grows into 

 a roundish hollow ball which gradually elongates and 

 develops the various organs of the cysticercoid ; when 

 the organs are fO'rmed, the larva retracts its scolex into 

 its cyst. In summer the entii'e development of the 

 cysticercoid lasts but two weeks, while in winter it 

 Iast.s over five weeks. 



Ducks naturally become infecled hy swallowini; llic 

 mussel crabs. 



