212 TAPEWORMS OF n ABES AND RABBITS— STILES. vouxix. 



6. The microscope must supplant the yardstick and internal anatomy 

 must take the place of external form in judging the validity of cestode 

 and trematode genera and si)ecies. 



7. The principle of homoiilasy must be recognized by helmintholo. 

 gists as well as by other zoologists, and any classilication which leaves 

 this important and well-recoginzed principle out of account can be taken 

 only as a preliminary (although often necessary) study (p. 204). 



8. The median field of the Taniiida- is the seat of the most active lat- 

 eral growth, and the same rulcAvill i)robably be found to apply to other 

 families of Cestoda. No particular longitudinal zone of the median lield 

 can, however, be named as the zone of most active growth in all 

 Ta'niidic (p. LH).")). 



9. The armed young cestode which I mentioned in Note 31' (1805) is 

 not the young of an anoplocephaline tapeworm, as Curtice, Braun, 

 Eailliet, Neumann, and 1 had inferred, but represents the young stage 

 of the single-pored cestode referred to in my paper in 1S95.- It evi- 

 dently belongs to Bavainea salmimi. 



10. The double pored cestode with occasional single pores, described 

 in my paper in 1895,'' is Citiotivnia variabilis anf/Ksta. 



11. I have also found some very young stages of an unarmed cestode 

 in the intestine of the cottontail rabbit, which ])robably belong to 

 Cittotania variahilis. This young stage corresponds to what we may 

 expect to tind as the larval form of Moniezia ex2)a)isa of cattle and sheep, 

 and I doubt whether it will be possible to distinguish it from the young 

 of that species. This renders the question of the origin of the tape- 

 worms of cattle and sheep more complicated than it was formerly sup- 

 posed to be, and demands the strictest esi)erimental proof on the part 

 of any author who suspects that he has solved the mysterj' of the life 

 history of the cestodes of cattle and sheej). 



12. The head of a cestode increases in size after the parasite 

 reaches its final host, as is shown by a comparison of the younger speci- 

 mens. 



13. None of the adult le[)orine tapeworms thus far described in Europe 

 have as yet been found in America. The American forms which have 

 been ])ublished as ^'- Twnia pectinata'^ must be distributed over several 

 species typical to this continent. 



14. The following table includes all of the genera at present recog- 

 nized in the subfamilies Ta'ui mm, Mesocestoidinje, Anoplocephalinie, and 

 T)i])ylidiina' of the family Taaiiida', A number of other genera have 

 been proposed, but some of them must fall as synonyms, while Judg- 

 ment upon otliers must be reserved. Several of the genera in this key 



1 Notes sur les Parasites — 31: Une phase pr^coce du Teuias dii T.npin, Bull. Soc, 

 zool. France, XIX. 1895, pp. 163-165. 



-Notes on Parasites — 36: A double-pored cestode with occasional single pores. 

 Centralbl. f. Bakteriol. u. Parasiteuk.. 1. Abt., XVII, 1805, pp. 457-459. 



^Loc. cit. 



