y8 SMITHSONIAN INSTITUTION 



ion by different observers, and even by the same observer from different points 

 of view. For instance, some of the characters cannot always be given the same 

 order of precedence in the tables. If we had genera showing every possible 

 combination we have discussed, it might be practicable to construct a table with 

 some uniform order of sequence. We do not, however, find all such combina- 

 tions, and it is quite conceivable that they were never all accomplished. But 

 it is also to be confidently expected that some additional ones will yet come to 

 light, and we can readily point out vacancies remaining to be filled by future 

 discoveries. 



The most important difference between the present and former arrange- 

 ments lies in the separation of Lecanocrinidae from Ichthyocrinidae, conse- 

 quent upon the discovery of the true dominating character of the latter, viz., 

 the suppressed infrabasals. The recognition of this relation cleared up the 

 most troublesome question that I had previously encountered in the classifica- 

 tion of the Flexibilia. 



