248 BULLETIN: MUSEUM OF COMPAKATIVE ZOOLOGY. 



Adelometra (Antedon angustiradia P. H. Carpenter). 

 aa. no pinnule on the third (epizygal) brachial. 



b. centro-dorsal discoidal, the few short and stout cirri in two or three 

 irregular marginal rows ; radials and lower brachials not tuber- 

 cular ; 10-30 arms 



Cyllometra (Antedon manca P. H. Carpenter). 



bb. centro-dorsal conical, the numerous elongate and slender cirri in 



more or less definite vertical rows ; costals and lower brachials 



strongly tubercular ; 10 arms 



Perometra (Antedon diomedeae A. H. Clark). 



