12 ANIMAL PAKASITES. 



replies to my inquiries, expressing doubts as to the existence of 

 a transition from the cestode to the trematodc worms, have 

 enabled me to come to the conclusion that Van Beneden does not 

 appear to aim at much more than what Vogt and Virchow have 

 done, namely, to show that lludolphi's classification of the worms, 

 founded merely upon differences of form, and not upon the 

 history of the development, was no longer tenable, and to intro- 

 duce a division into the system, which should place the relation- 

 ship between the cestode and trematode worms in a clearer 

 light. I shall hereafter combat the belief in an actual transition 

 between the Cestoidea and Trematoidea, and have endeavoured 

 to give here a classification which may perhaps furnish a more 

 exact representation of the affinities of these two kinds of worms, 

 and reconcile the contradictorv statements of authors, and which 

 closely approaches the views maintained years ago by Valisneri 

 and others, and more recently by Eschricht, Leuckart, &c. 



A. PLATYELMIA. 



Entozoa solitaria aut composita, androgyna. Corpus depressum 

 vel teretiusculum, molle, organis ad fixandum aptis prceditum. 

 Anus nullus ; canalis cibarius aut divisus (rarissime simplex), aut 

 nullus. Cavitas corporis no?i distincta. Metamorphosis in pie- 

 risque ; larva gemmiparce aut sporuliparce. (Leuckart, in Van der 

 Hoeven.) 



First Sub-class. 



Cestoidea = Cephalocotylea (Diesing) =Bandwiirmer ( = Tape- 

 worms) = Platyelmia composita, aut colonias exhibentia = 

 Plattwurmcolonien (mihi), Flat- worm-colonies (inch Cysticis). 



Animalia tomotoca, per longum plerumque tempus larva 

 nutrici juncta et una cum ea corjms elongatum, ariiculatum, 

 polymorphum formantia. Larva (Scolex, vulgo caput) pyrifonnis, 

 foveis aut osculis suctoriis 4 vel 2 instructa, sce/nssime uncinata. 

 Proles sexualis (Proglottides, vulgo articidi) organis externis desti- 

 tuta, embryones nucinulis armatos gignentes. Canalis cibarius 

 nullus. (Leuckart, in Van der Hoeven.) 



