2 SMITHSONIAN INSTITUTION 



ing in important additions to our knowledge of this group. And the broader 

 grasp of the subject consequent upon this increase of knowledge has enabled me 

 to place on a firmer basis certain family divisions, which would have been left in 

 an unsatisfactory condition if I had published my results a few years ago. 



I think it only fair to observe further, by way of personal allusion, that I 

 have labored under the disadvantage of a lack of practical zoological training, 

 which compels me to limit my treatment of the subject chiefly to the presenta- 

 tion of the facts from a systematic standpoint, without venturing far into the 

 field of evolutionary interpretation. This I prefer to leave to others who are 

 better qualified to undertake it, and it is my hope that this contribution to the 

 sum of knowledge of these organisms may be of some service to those who 

 engage in more general discussions. 



It was evident to me at the outset that the plan of restricting the detailed 

 investigation of this group to its American representatives, as was done in the 

 treatise on the Camerata by Wachsmuth and myself, was unsatisfactory. I 

 have therefore endeavored to include in this work all known species of Flexi- 

 bilia, from whatever areas they may be derived. Such an enlargement of the 

 scope of the research added materially to the labor and difficulty of its prosecu- 

 tion, inasmuch as it became imperative to obtain accurate information in regard 

 to the specimens contained in foreign collections. The most important in rela- 

 tion to the present group of the Crinoidea are those in England, Sweden, Bel- 

 gium and North Germany. 



Collections 



It was my good fortune, thanks to the courtesy of the authorities in charge 

 of them, to whom I am under a heavy obligation, to be able personally to study 

 the material in most of the principal collections of those countries. First 

 among these is that of the British Museum, containing the original collections 

 of Gilbertson, Lord Enniskillen, Sir Philip Egerton, Mr. John Gray and others, 

 including many of the types of Phillips, and specimens studied by Bather in the 

 course of his various investigations; I have enjoyed the advantage of frequent 

 communication and of personal conferences with Dr. Bather during the period 

 of my studies on the Flexibilia, and he has with great generosity turned over 

 to me for description some interesting specimens belonging to this group which 

 he had himself proposed to describe. Other important material was furnished 

 from the rich collection of Wenlock crinoids in the Dudley Museum, and the 

 equally important collection from the same locality made by Mr. Charles 

 Holcroft now belonging to the Museum of Birmingham, as well as from 

 another by Mr. William Madely. These Silurian crinoids from the typical 

 locality at Dudley were supplemented by a very fine series secured by myself 

 from several private collections made in that vicinity during the years when the 

 quarrying operations were most productive. The original collection of the 



