MONOGRAPH OF THE EXISTING CKINOIDS. 19 



dia<rrammatic 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 loss distorted picture before 

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



All the fit^ures included herein have been prepared in Ime ^\'^th these ideas, 

 and future workers will be able to determhie 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 

 becomhig swamped m a multiplicity of detail opened up an additional series of 

 problems It has seemed to me ample m the case of the flat 10-armed comastends 

 to show one-fifth of the aifimal (two arms) hi dctaU, includmg the centrodorsal 

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

 indicate the remaming portions by shnple Imes; m the case of very many armed 

 forms the sketchmg m of tne arms m the additional four sectors has the effect of 

 dmfinishmg the strength of the detailed sector, as well as by hicreasing the width 

 of the figure, necessitatmg a somewhat greater reduction m size than is advisable. 

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



species are therefore shown. _ ■ x-u •■ „„ 



In the preparation of the text figures, I was fortunate m securuig the coopera- 

 tion of iliss Violet Dandridge, of Shepherdstown, West Virgmui whose expenence 

 m preparmg figures abounding m detaU, especially of shells, fish, and ophiuroids, 

 formed the best possible basis for work upon the crmoids. 



The photographs for the plates were made by ilr. T. W. Smilhe m the photo- 

 graphic department of the United States National Museum. 



IDENTIFICATION OF THE SPECIMENS UPON WHICH THIS WORK IS BASED. 



Almost all the spechnens which have been exanfined by the author in the 

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

 and all are herem listed under theh 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 herem given have been founded 



The letters foUowhig the data for each specimen mdieate the collection m 

 which the specimens may be found, as foUoTiv-s: 



Ampr M • American Museum of Natural History, New York. 



Austr'. M. : Austrahan Museum, Sydney, New South Wales. 



g M _ : British Museum. 



Bei-g M.: Bergen Museum. 



Berl M ■ Museum f iir Natm-kunde, BerUn. 



B s"- ' Museum of the Boston Society of Natural llistory. 



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



j)_ M. : Dresden Museum 



E.I.: 



Museum of the Essex Institute, Salem, Massachusetts. 



Y g . Frank Springer collection. 



