A MONOGRAPH OF THE EXISTING CRINOIDS 



By Austin Hobart Clark 

 Curator, Division of Echinoderms, United States Nationo. Mvsenm 



INTRODUCTION 



In the introduction to Part 1 of Volume 1 (pp. 21-55) the evolution of the study 

 of the systematic interrelationships of the comatulids was traced in detail up to the 

 year 1910, but the history of the development of the scheme of classification now in 

 use from its first inception in 1907 was reserved until the present time. 



The development of the knowledge of the interrelationships of the comatulids 

 up to 1907 may be briefly recapitulated as follows. 



Llhuyd pointed out in 1699 and in 1703 that the rosy feather-star {Antedon bifida) 

 is the sea star to which the fossil crinoids are most closely related. In 1733 Linck 

 separated the comatulids from the starfish and serpent stars and distributed the six 

 species known to him among three genera based upon the number of arms. But in 1758 

 Linne again placed the comatulids with the starfish and ophiurans in the genus Asterias. 



In order to emphasize its distinctness from the ophiurans with which it was 

 presumably then associated in the minds of naturalists, de Fr^minvUle in 1811 

 created the genus Antedon to receive the common comatulid of the European coasts. 

 In 1815 Leach suggested the genus Aledo, including the three species of comatulids 

 with which he was acquainted, and in 1816 Lamarck proposed the genus Comatula, 

 in which he placed all the comatulids known to him. 



Agassiz in 1836 published the genus Comaster, based upon Lamarck's Comatula 

 muUiradiata, of which the only character given was the excess of the number of arms 

 over 10. In 1841 Miiller described the genus Adinometra, which was based upon 

 the arrangement of the ambulacral grooves upon the disk and evidentlj' intended 

 to include all the exocyclic species, or comasterids. In 1866 Lov^n instituted his 

 new genus Phanogenia, the chief character of which was the great reduction of the 

 centrodorsal and the absence of cirri, and in 1868 Semper described the genus Ophio- 

 crinus (the name being preoccupied was subsequently changed by P. H. Carpenter 

 to Eudiocrinus) , including a species with only 5 arms. 



In 1879 P. H. Carpenter proposed the genus Promachocrmus, including species 

 with 10 instead of 5 radials; in 1881 the genus Atelecrinus with externally visible 

 basals; and in 1884 the genus Thaumatocriniis with large orals, a completely plated 

 disk, and interradials, of which the posterior bears a short jointed process. 



Thus at the time of the publication of the Challenger report in 1888 there were 

 in the literature the following 10 genera of comatulids: 



Antedon. Phanogenia. 



Aledo. Ophiocrinus (Eudiocrinus). 



Comatula. Promachocrinus. 



Comaster. Atelecrimis. 



Adinometra. Thaumatocrinus. 



97298—31 2 1 



