niEFACE. 



This piipcr is the result of studies begun many years ago, with a 

 view to clarifying the record of the crinoid forms herein discussed 

 from the confusion growing out of the excessive activity of some 

 authors in species making. The drawings of the Miller and Gurley 

 types, and those for plates 1 to 4 on Comantliocnnus, Hadrocrinus, 

 and Himerocrinus, were made by Mr. Kenneth M. Chapman of 

 Santa Fe, New Mexico. The text-figures were prepared by my 

 assistant, Dr. Herrick E. Wilson. In the preparation of the other 

 figures upon Dolatocrinus I have had the assistance of Dr. R. S. 

 Bassler in photographing the specimens, and of Miss Francesca Wieser, 

 of the United States Geological Sm'vey staff, in retouching the prints,, 

 for which I extend to them my sincere thanks. 



Washington, D. C, April J, WW. 



