510 CLARK: THE CRINOID FAMILY ANTEDONIDAE 



the radial areas being separated by high 

 ridges (From St. Lucia, British West Indies, 

 northward to Georgia and Pensacola, Florida; 



304-792 meters) Zenometra 



Three columns of cirrus sockets in each radial area, 

 the radial areas being separated by broad bare 

 areas (Hawaiian Isla?ids; 346-633 meters). 



Sarametra 

 Size small; cirri with less than 30 segments; columns of 

 cirrus sockets on the centrodorsal slightly irregu- 

 lar; interradial areas on the centrodorsal not es- 

 pecially differentiated (Marion Island, and the 

 shores of the Antarctic continent in the vicinity of 

 Gaussberg; 252-400 meters) Eumorphometra 



Subfamily ISOMETRINAE A. H. Clark 



• 



The only genus in this subfamily islsomelra, of which a complete 

 account will be found in Die Crinoiden der Antarktis,^. 145-146. 4 



Subfamily BATHYMETRINAE A. H. Clark 

 Key to the Genera of the Subfamily Bathymetrinae 



All the cirrus segments short, the longest not so much as twice as long 

 as the median diameter. 

 Cirrus segments cylindrical, without expanded distal ends, 25-33 

 (usually nearer the latter) in number, the longest (third- 

 fifth) about one-third again as long as broad, those beyond 

 the eighth about as long as broad, the distal slightly broader 

 than long; IBr series and arm bases without lateral proc- 

 esses, and widely free laterally (Western coast of Ireland; 



698 meters) Orthometra 



Cirrus segments with much swollen distal ends, not more than 20 

 in number; IBr series and brachials in close lateral contact 

 (Moluccas to Marion Island, southeast of Africa; 1089-2880 



meters) Tonrometra 



Proximal cirrus segments elongated, at least twice as long as the me- 

 dian diameter, and usually much longer. 

 Centrodorsal sharply conical with straight sides, nearly or quite 

 as long as broad at the base (Philippine Islands to Celebes; 



509-1901 meters) Fariometra 



Centrodorsal less sharply conical, with rounded sides, or hemi- 

 spherical, and lower. 

 All the brachials have strongly produced and very spinous 

 edges; Pi very slender and delicate, markedly longer 

 than P 2 , with the outer segments very greatly elon- 



'Deutsche Siidpolar-Expedition, 16 (Zoologie, 8), May 16, 1915. 



