May 25, 1921 From United States Covernment ADVERTISEMENT. The scientific publications of the United States National Museum consist of two series, the Proceedings and the Bulletins. The Proceedings, the first volume of which was issued in 1878, are intended primarly as a medium for the publication of original and usually brief, papers based on the collections of the National Museum, presenting newly acquired facts in zoology, geology, and anthropology, including descriptions of new forms of animals and revisions of limited groups. One or two volumes are issued annually and distributed to libraries and scientific organizations. A limited number of copies of each paper, in pamphlet form, is distributed to specialists and others interested in the different subjects as soon as printed. The date of publication is recorded in the table of contents of the volume. The Bulletins, the first of which was issued in 1875, consist of a series of separate publications comprising chiefly monographs of large zoological groups and other general systematic treatises (occasionally in several volumes), faunal works, reports of expeditions, and catalogues of type specimens, special collections, etc. The majority of the volumes are octavos, but a quarto size has been adopted in a few instances in which large plates were regarded as indispensable. Since 1902 a series of octavo volumes containing papers relating to the botanical collections of the Museum, and known as the Contributions from the National Herbarium, has been published as bulletins. The present work forms No. 115 of the Bulletin series. Administrative Assistant to the Secretary, PREFACE. This paper 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 Comanthocrinus, 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 Survey staff, in retouching the prints, for which I extend to them my sincere thanks. WASHINGTON, D. C., April 1, 1920. III |