Structure and Development of Cestoda. 1 Of the unseg- 

 inented Cestodes, Caryopliyllaeus mutabilis, from the intestine of 

 carp and other Cyprinoid fishes, is the most easily accessible form. 



FIG. 40. A, Stickle- 

 back (Gasterosteus 

 aculeatus) infested 

 by an advanced 

 larva of Schisto- 

 cepluihts solidus 

 Crepl. B, The 

 larva. All x 1$. 

 (From specimens 

 in the Cambridge 

 University Mu- 

 seum. ) 



Triacnophorus nodulosus, which is very useful for the study of the 

 excretory system, occurs mature in the pike. In the body-cavity of 

 the Stickleback ( Fig. 40) a large, broad, yellow worm may sometimes 



1 Moiiit-z, "Sur les Cysticenjucs," Paris, 1880; LI. "Sur les Cestodcs," 1881 ; 

 Xschokkc, " Recherches sur i* structure auatomii^ui* et histologujue d. Cestodes," 

 Geneve, 1888. 



