210 TAPEWORMS OF HARES AND RABBITS STILE '. 



of our colleagues, but it would be going a little far to assume that 

 we did not have other forms in mind at the time we revised a por- 

 tion of the species known to us. Consistency being such a virtue, 

 however, if Meyner considers the species mentioned in the former 

 papers by the authors he criticises as representing the sum total of 

 the species known to them, he will probably not object to applying the 

 same criterion to himself. As he has published original work on only 

 two species, however, it might be difficult for him to justify himself in 

 attempting upon the basis of these two species to overthrow the con- 

 clusions which have been based upon a study of a much larger number 

 of forms by four different specialists, all of whom agree in the general 

 arrangement and differ with each other only in matters of detail. 

 Meyner's remarks represent an excellent example of what is so com- 

 mon in science to-day, namely, a tendency to jump at conclusions and 

 to generalize in a too dogmatic manner when one is not thoroughly at 

 home on the subject he has under discussion. 



The above remarks are, I think, sufficient to show that Meyner's 

 amusing criticisms would better have been submitted to more careful 

 thought before they were published. They can not have much weight 

 with helminthologists, and should not have much weight with zoolo- 

 gists in other specialities. 



A number of genera not discussed in this paper have been proposed 

 by authors for various forms in the family Tasniidse. Some of these 

 genera must be rejected. In regard to f some of the others, judgment 

 must be reserved for the present. I hope, however, to publish before 

 long a summary of all the genera proposed. Regarding the newly pro- 

 posed genera for avian cestodes, see Stiles, 1 1896. 



Exchange of cotypes. There seems to be a popular impression among 

 workers that it is a perfectly easy matter for a scientist to read a 

 description of a species or genus and judge of the validity of the pro- 

 posed form without examining specimens. This impression is certainly 

 true in some cases, but must always be taken cum grano salis. I do not 

 hesitate to assert that not one-half of the species and genera of parasitic 

 worms ever described can be rightly judged from their descriptions, nor 

 is this always attributable either to the description or to the ability of 

 the worker attempting to pass judgment upon the case. It is rather 

 attributable to the undeniable fact that a person obtains an entirely 

 different impression from a study of the objects from what he obtains 

 from reading a description, be it ever so detailed and complete. Many 

 a species or genus has been accepted or rejected by an author who would 

 have decided differently if he could have examined cotypes of the 

 forms he was discussing. 



In view of these facts, which I am confident the specialists in hel- 

 minthology will admit, I wish to appeal again to helminthologists to 



1 Report upon the present knowledge of the tapeworms of poultry, Bull. 12, Bureau 

 Animal Industry, Washington, D. C. 



