575 



figures have been cousulted as far as possible aud data 

 derived from tlieui have been combined with more re- 

 cent diagnoses and descriptions. 



It would be well if authors making- and publisliiug 

 specific determinations in this group would preserve 

 their specimens in some way, so that they may be used 

 by later writers on the subject, for in many C'f the 

 species described below the determination can be 

 looked upon only as approximate and provisional. 

 The specific determination of these forms is of much 

 greater importance from a practical standpoint than 

 is generally assumed, for an exact knoAvledge of the 

 species is necessary as a foundation for general pre- 

 ventive measures. 



Nomenclature. — In several places where it is per- 

 fectly evident that the parasites are now sailing under 

 wrong names, I have corrected the names according to 

 the international rules. In the majority of cases, hew- 

 ever, I postpone changes until I can complete a revi 

 sion of the entire group based upon original material. 



In the systematic arrangement given below keys are 

 given not only to the species of adult tapeworms o-f 

 domestic fowls, but also to some closely allied forms. 

 The allied genera and sub-families are given in the 

 keys in order to show the general relationships of the 

 group. 



The tapeworms of fowls belong to two families, the 

 Ho'thriocephalidae and Taeniidae. 



Regarding the generic position of the tapeworms of 

 domesticated fowls it may be stated that up to within 

 very recent years nearly all of the forms have been 

 ])laced in the collective genus Taenia. To R. Blan- 

 chard and A. Railliot is due the chief credit of pointing 

 out the absurdity of uniting these forms genonrnllv 



