INTRODUCTION. 



In connection with the collection made by the "Albatross" Expedition 

 of 1891, I intended to take up the anatomy of the most prominent types 

 of the Deep Sea Echini, combining with it species from the collections made 

 by the "Blake," the "Hassler," and other "Albatross" Expeditions. Con- 

 siderable material had been brought together to elucidate the structure of 

 the pedicellariie, of the spines, the jaws, the auricles, and internal anatomy 

 of groups represented by deep-sea species. Unfortunately my frequent 

 and prolonged absences in the interest of Thalassographical investigations 

 have interfered to such an extent with this work that 1 am again com- 

 pelled to postpone that part of my Report to another occasion. Having 

 associated with this investigation Professor Hubert Lyman Clark, of Olivet, 

 Michigan, I hope to incorporate this material in a Report on the Echini 

 collected by the " Albatross " among the Hawaiian Islands which we are 

 preparing for the United States Fish Commission. 



The present Report on the Echini of the "Albatross" Expedition of 

 1891, the greater part of which was written in 1898, is therefore published 

 without the studies mentioned above, and limited principally to the morpho- 

 logical study of the tests of the species discovered. I regret the delay of 

 the publication of the details; the more so as two Memoirs 1 have lately 

 been published which deal with the classification of the Echini essentially 

 from the study of the pedicellaria?. These Memoirs are both very radical 

 in their conclusions, and are likely, if adopted without further criticism, to 

 increase the confusion already existing in the classification of Echini, which 

 the authors attempt to rectify. 



The Monographs are both by new-comers into the field of Echinology, 

 enthusiastic in their cause, and showing but little appreciation of the work 

 of those who have preceded them. Dr. Mortensen practically rejects all 



1 The Danish " Ingolf " Expedition. Vol. IV. 1. Echinoidea. Part T, by Th. Mortensen, 1903. 

 Siboga-Expeditio. I >ie Echinoidea der Siboga-Expedition, v. J. C. H. De Meijere. 1901. 



