CLARK: THE CRINOID FAMILY ANTEDONIDAE 509 



and the last will be found in my memoir on Die Crinoiden 

 der Antarktis. 3 



Subfamily ZENOMETRINAE A. H. Clark 

 Key to the Genera of the Subfamily Zenometrinae 



Pi and P a absent (Philippine Islands; 140-148 meters) Balanometra 



Pi and P a present. 



Cirri with all the segments elongated, the distal entirely without 

 dorsal processes; or (very rarely) a few of the outermost 

 cirrus segments may be but little longer than broad with 

 slight dorsal tubercles. 

 Cirrus sockets arranged in closely crowded columns in each 

 radial area; but the groups of columns in each radial 

 area are usually (almost invariably) separated from 

 the groups of columns in the adjacent radial areas by 

 long triangular bare patches; the distal cirrus seg- 

 ments are always greatly elongated, never with any 

 trace of dorsal processes (Fro?n the Galapagos Islands 

 and Panama northward to the Aleutian Islands, and 

 southward on the Asiatic coast to Yezo Strait and the 

 northern part of the Sea of Japan; the Hawaiian Islands; 

 the Philippine Islands; the Lesser Sunda Islands; the 

 Bay of Bengal and the coast of Travancore, and. south- 

 ward to the Antarctic regions; 336-2858 meters) 



Psathyrometra 

 Columns of cirrus sockets somewhat irregular, and evenly 

 spaced all around the centrodorsal without differentia- 

 tion into radial groups;. the distal cirrus segments may 

 be much elongated with no trace of dorsal processes, or 

 little, if any, longer than broad, with slight dorsal 

 tubercles {From the western coast of Scotland, and 

 Ireland, southward to Madeira, including the entire 

 Mediterranean basin; 45-1292' meters) . . . . Leptometra 

 Cirri with the proximal segments more or less elongated, but the 

 distal segments short, never longer than broad, and bearing 

 prominent dorsal processes. 

 Division series and arm bases smooth; 10-14 arms (Kei 

 Islands and northern Cuba; 252-380 meters) 



Adelometra 

 Division series and arm., bases spiny. 



Size large; cirri with more than 40 (50-60 segments; 



columns of cirrus sockets very regular, separated 



interradially by high ridges, or by broad bare areas. 



Two columns of cirrus sockets in each radial area, 



3 Deutsche Sudpolar-Expedition, 16 (Zoologie, 8), May 16, 1915, pp. 120-143. 



