504 CLARK: THE CRINOID FAMILY ANTEDONIDAE 



ZOOLOGY. — The interrelationships of the subfamilies and genera 

 included in the crinoid family Antedonidae. 1 Austin H. 

 Clark, National Museum. 



Recently in the pages of this Journal 2 I proposed a rear- 

 rangement of the species of Antedonidae, distributing them 

 among forty genera, which in turn were grouped in seven 

 subfamilies. 



In the following keys the interrelationships of the subfamilies, 

 and of the genera within each, are shown. 



Family ANTEDONIDAE Norman (emended) 

 Key to the Subfamilies of the Family Antedonidae 



Cirrus sockets arranged in definite columns on a conical or columnar, 



usually large, centrodorsal Zenometrinae 



Cirrus sockets arranged in transverse alternating rows, or irregularly, 

 on a hemispherical to discoidal or conical centrodorsal. 

 The segments of the genital pinnules are much expanded, forming 



a roof over the gonads Isometrinae 



The segments of the genital pinnules are not expanded. 



Pi is composed of numerous (usually more than 50 and never 

 less than 30) short segments of which at least the first 

 six or seven, and usually nearly all, are broader than 

 long, and the distal are rarely more than twice as long 

 as broad; Pi is about as long as, or longer than, P 2 . 

 One or more of the following pinnules resembles Pi. 



Heliometrinae 



P 2 and the following pinnules are composeel of segments 



which, beyond the third or fourth, are much 



elongated Thysanometrinae 



Pi is composed for the most part of much elongated segments, 



though a few of the basal segments may be short; the 



distal segments are at least twice as long as broad. 



The distal cirrus segments are entirely without dorsal 



processes on their distal ends; the cirri are usually 



(but not always) short, rarely with more than 20, 



never with more than 30, segments. . Antedoninae 



The distal cirrus segments always have the distal dorsal 



edge prominent, with the meelian portion more or 



less proeluced in the form of a dorsal spine, and 



the mid-dorsal line more or less strongly carinate. 



1 Published with the permission of the Secretary of the Smithsonian Insti- 

 tution. 



2 Journ. Wash. Acad. Sci., 7: 127-131. 1917. 



