PART S A MONOGRAPH OF THE EXISTING CRINOIDS 653 



the proportions of the cirrus segments intermediate between those found in the other 

 genera, three alternatives rather than the usual two were inserted at this point (6). 



Finally the genus Orthometra is so little known, particularly with regard to the 

 pinnules, that I cannot find any character to support the geographical range which 

 will distinguish it from all the species of Tonrometra. 



KEY TO THE GENERA OF BATHYMETRINAE 

 [modified by A.M.C.] 



a 1 . The female with a marsupium in the form of a pouch on each genital pinnule (off Uruguay to the 

 South Shetlands, South Georgia and Marion Island; 137-1097 meters) --Phrixometra 9 (p. 653) 

 a 2 . No marsupium present. 



ft 1 . The longest segments of the peripheral cirri two to three times as long as broad, the distal segments 

 as long as broad or a little longer; Southern Ocean; P] with markedly flared and spinous 

 distal ends to the segments; up to 25 cirrus segments (off Uruguay to the South Shetlands, 

 South Georgia and Marion Island; 137-1097 meters) Phrixometra rf 1 (p. 653) 



6 2 . Longest cirrus segments up to three times as long as broad, distal segments not longer than 



broad; if from the Southern Ocean then PI has the segments hardly at all enlarged at the 

 joints and the peripheral cirri have 25-37 segments. 

 c 1 . PI with over 20 segments. 



(P. Peripheral cirri with up to 30 segments; PI with about 30 segments of which the first five to 



seven are not longer than broad (SW. Japan; 195 meters) Boleometra (p. 665) 



d 3 . Peripheral cirri with 30-45 segments; PI with up to 25 segments of which not more than 



three (or four) are not longer than wide. 

 e 1 . PI distinctly shorter than P! and with many fewer segments (Cuba to Greenland, Iceland, 



the Faroes and south to Portugal; 256-2193 meters) Trichometra (p. 668) 



e 2 . P 2 similar in size and number of segments to PI (Antarctic; 1266 meters). 



Tonrometra spinulifera (p. 686) 



r 2 . Pj with up to 20 segments. 



d 1 . Division series and proximal brachials with smooth distal edges (Meangis Islands, East 



Indies; 914 meters) Nepiometra (p. 678) 



d?. Division series and proximal brachials more or less flared and spinous at the distal edges. 



e 1 . NE. Atlantic; 698-987 meters Orthometra (p. 680) 



e 2 . Southern Ocean and East Indies; 1089-3426 meters Tonrometra (p. 682) 



6 3 . Longest cirrus segments two and a half to six times as long as broad, the distal segments also 



longer than broad. 

 c 1 . Only X-XV cirri (south from Australia and north from Midway Island, North Pacific ; 4753-5301 



meters) Bathymetra (p. 691) 



c 2 . XXV or more (usually XXX-XL) cirri. 

 d 1 . PI with 25 or more segments. 

 e 1 . Pj much shorter than PI. 



/'. 12-20 cirrus segments (off Alaska; 291-1270 meters) Betiometra (p. 695) 



/ 2 . 24-33 cirrus segments (Chesapeake Bay to southern Greenland, Iceland, Ireland, 

 north of Scotland and the Scandinavian coast from western Sweden to East 



Finmark; 28-1783 meters) Hathrometra (p. 698) 



e 2 . P 2 little shorter than P, (Japan Sea area; 146 (?100)-1500 meters). 



Thaumatometra tenuis (p. 744) 

 d 2 . PI with less than 25 segments. 



e 1 . Cirri with 21-36 segments (East Indies, Arabian Sea and southern India and from 



Panama to Southern California; 204-2194 meters) Fariometra (p. 723) 



e 2 . Cirri with 10-20 segments (from the Southern Ocean to India, the East Indies, Japan, 

 north to the Bering Sea, from Greenland to Iceland, from Brazil and from north of 

 New Zealand (? from Panama); 274-3239 meters) Thaumatometra (p. 742) 



