x INTRODUCTION. 



the work of his predecessors, and challenges it all as worthless because it is 

 not based upon his methods for the solution of all Echinological problems. 

 Like all classifications based upon a single character, the results obtained 

 culminate in such impossible associations that we are loath to follow his lead. 

 But as the material at my disposal has only been partly worked up, I do 

 not propose to discuss at present the questions raised by Dr. Mortensen 

 beyond calling attention to some points suggested by the study of the few 

 genera involved in this Report ; others I hope to take up in a subsequent 

 Memoir. 



I must protest against the temper and style of criticism adopted by 

 Dr. Mortensen ; even if he were right, his assumption of omniscience is 

 offensive to the utmost, and his personal remarks are entirely out of place 

 in a scientific memoir. 



I am tempted to quote, mutatis mutandis, from an article in a New York 

 newspaper summing up the arguments against old fogies' views propounded 

 by an ardent reformer: '' The results should diminish the patronizing cer- 

 tainty of -knowing it all' which distinguishes Dr. Mortensen's work, and 

 forbids us, his predecessors, to discuss matters of which we must be. in the 

 nature of the case, wholly ignorant" ! 



To faciliate references to the plates, I have intercalated in the text a 

 large number of figures, on which I have adopted, for the sake of brevity. 

 Loven's nomenclature of the plates of the test of Echini. I wish, however, 

 to repeat that in doing so I do not accept the theoretical conclusions attached 

 by Loven to his nomenclature. My reasons for doing so have been fully 

 stated in the " Challenger" Echinoidea Report, p. 4. 



I have specially to thank Mr. A. M. Westergren for the great care he has 

 taken in preparing the drawings for the lithographic plates which accompany 

 this Memoir. I am also under great obligations to him for his general super- 

 intendence of the execution of the plates. 



Newport, R. I., August, 1904. 



