CLARK: NEW GENERA OF ECHINODERMS 115 



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ZOOLOGY. — Seven new genera of echinoderms. 1 Austin H. 

 Clark, National Museum. 



The past ten years has witnessed an activity in the study of 

 the echinoderms far surpassing that of any previous decade. 

 In] every class important and comprehensive memoirs, many 

 of them monographic in scope, have been published which in- 

 clude more or less complete revisions of genera, of families, 

 and of higher groups. Little by little the former wide differences 

 of opinion in regard to the internal systematic arrangement in 

 each class have disappeared, and today such diversity as exists 

 chiefly relates to the refinement of generic limits and the allo- 

 cation of a few anomalous types. 



Along these lines there is still much work remaining to be 

 done, and it is in the hope of throwing additional light on cer- 

 tain obscure points that I am calling attention to the following 

 four crinoid and three starfish types which appear to me to be 

 well worthy of generic rank. 



Comatonia, new genus 



Genotype. — Actinometra cristata (P. H. Carpenter, MS.) Hartlaub, 

 1912. 



A genus of Capillasterinae (Comasteridae) in which the size is small; 

 there are 10 arms only; the cirri are not excessively slender; there are 

 no carinate processes on the basal segments of the proximal pinnules; 

 terminal combs occur only on the pinnules of the first pair (Pi and P2), 

 from one or both of which they may be absent; the combs usually arise 

 about, or within, the proximal third of the pinnule, and are composed of 

 exceptionally large rounded teeth which usually much exceed in height 

 the lateral diameter of the segments which bear them; the fourth-seventh 

 brachials bear prominent spinous median knobs or keels; usually one 

 or more of the earlier segments of P x are twice as long as broad, or even 

 longer. 



The only species of this genus, Comatonia cristata (Hartlaub), 



ranges from North Carolina to Key West, Florida, in from 1\ to 132 



fathoms. 



Austrometra, new genus 



Genotype. — Oligometra thetidis H. L. Clark, 1909. 



This new genus of Colobometridae is most closely related to Anal- 

 cidometra, with which it agrees in possessing expanded genital pinnules, 

 a character not known elsewhere in the family. Both Austrometra 



1 Published with the permission of the Secretary of the Smithsonian Institution. 



