MONOGRAPH OF THE EXISTING CKINOIDS. 19 



diagrammatic by the arbitrary arrangement of the arms in a given position, com- 

 parison of the figures inter se would be greatly facilitated; it would not then be 

 necessary to use the imagination in righting a more or less distorted picture before 

 comparison could be made with another equally, but differently, distorted. 



All the figures included herein havo born prepared in line with these ideas, 

 and future workers will be able to determine whether or not they are of any value. 



While the portrayal of 5 or 10 armed species which normally carry their arms 

 at more or less of an angle to the surface of the disk is a comparatively simple 

 matter, the question of how to show a multibrachiate or a flattened species without 

 becoming swamped in a multiplicity of detail opened up an additional series of 

 problems. It has seemed to me ample in the case of the flat 10-armed comasterids 

 to show one-fifth of the animal (two arms) in detail, including tho centrodorsal 

 and such cirri as may be present on the side opposite the arms as drawn, and to 

 indicate the remaining portions by simple lines; ha the case of very many armed 

 forms the sketching in of tiie arms in the additional four sectors has the effect of 

 diminishing the strength of the detailed sactor, as well as by increasing the width 

 of the figure, necessitating a somewhat greater reduction in size than is advisable. 

 Only the central portion and one of the so-called "rays" of the multibrachiate 

 species are therefore shown. 



In the preparation of the text figures, I was fortunate in securing the coopera- 

 tion of Miss Violet Dandridge, of Shcphcrdstown, West Virginia, whose experience 

 in preparing figures abounding in detail, especially of shells, fish, and ophiuroids, 

 formed the best possible basis for work upon the crinoids. 



The photographs for the plates were made by Mr. T. W. Smillie in the photo- 

 graphic department of the United States National Museum. 



IDENTIFICATION OP THE SPECIMENS UPON WHICH THIS WORK IS BASED. 



Almost all the specimens which have been examined by the author in the 

 preparation of this report have been marked with a small label stating the fact, 

 and all are herein listed under their respective species, so that any future worker 

 may be able to consult, with the least possible trouble, the material upon which 

 all the statements and deductions herein given have been founded. 



The letters following the data for each specimen indicate the collection in 

 which the specimens may be found, us follows: 



Amor. M. : American Museum of Natural History, New York. 



Austr. M.: Australian Museum, Sydney, New South Wales. 



B. M. : British Museum. 



Berg. M. : Bergen Museum. 



Berl. M. : Museum f iir Naturkun.de, Berlin. 



B. S. : Museum of the Boston Society of Natural History. 



C. M. : Zoological Museum, Copenhagen, Denmark. 



D. M. : Dresden Museum. 



E. I.: Museum of tho Essex Institute, Salem, Massachusetts. 



F. S.: Frank Springer collection. 



