PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 129 



segments of bijida are equally as spinous in some specimens as those of loveni and the 

 nimiber of segments in Pi seems to be little higher in small examples of bifida than in 

 loveni of similar size. A proper assessment of their relationships will have to await 

 another occasion when more material of loveni and of the other species formerly in- 

 cluded in Comj^sometra can be compared with precise details of the characters of Atlantic 

 species in relation to size. 



KEY TO THE SPECIES OF ANTEDON 



[Modified by A. M.C.] 

 a'. Cirrus segments not more than 18, rarely over 16. 



bK Pj intermediate in length between Pi and P3, though sometimes little longer than P3; cirri 

 usually XL or more (western Sweden and the coast of Norway north to about 70° and 



from the Faroes and south-west of Iceland; 27-326 meters) petasus (p. 130) 



i)2. Pj similar in size to P3, or smaller; cirri usually about XXX, rarely exceeding XL. 



c'. Pj a genital pinnule and as much as two-thirds as long as Pi (West Indies; 364-429 meters). 



nuttingi (p. 143) 

 c'. P2 rarely a genital pinnule and not more than half as long as Pi. 



d'. Cirrus segments more or less attenuate, the longest well over twice as long as their median 

 width. 



c'. Cirri with 12-17 segments (the Moluccas to Flores; 0-95 meters) longicirra (p.l45) 



e'. Cirri with not more than 12 segments. 

 /'. Pi with 8-11 segments; arm length up to 35 mm. but rarely known to exceed 20 mm. 

 (East Indies to the Bonin and Maldive Islands; 0-275 [?400] meters). 



parviflora (p. 147) 

 p. P] with about 17 segments; arm length up to at least 45 mm. (off Malaya to Queens- 

 land, Australia; 0-55 meters) iris (p. 151) 



d'. Cirrus segments not more than about twice as long as wide, usually shorter. 



e'. Cirri relatively long, equal to about a fourth the arm length, with up to 18, usually 16, 

 segments, the longest about twice as long as their median width or slightly longer, 

 the dorsoventral expansion towards the distal end not very well marked so that 

 the median width of the widest segments is only about a third again that of the nar- 

 rowest, more proximal, ones; cirri often preserved with the outer half uncurled (Sierra 



Leone to Gabon in the Gulf of Guinea; 0-120 meters) hupferi (p. 153) 



e'^. Cirri short, usually equal to about a fifth the arm length, with rarely more than 16 

 segments, the longest usually less than twice as long as wide, the widest segments 

 about half to two-thirds again as wide as the narrowest ones in most specimens; cirri 

 usually preserved in a curled condition. 

 /'. Rarely more than 14 cirrus segments; from the Indo-West Pacific. 



5'. Centrodorsa! discoidal, dorsal pole flat; antepenultimate cirrus segment not longer 



than wide (south and west Austraha) incommoda (p. 157) 



hK Dorsal pole large, the sides of the centrodorsal nearly vertical (south-east [7 to 



south-west] Australia; 0-68 meters) incommoda incommoda (p. 157) 



h'. Dorsal pole smaller (north-west Australia) incommoda austini (p. 162) 



g2. Centrodorsal hemispherical to rounded conical, the dorsal pole more or less convex; 

 antepenultimate cirrus segment usually longer than wide. 

 hK Cirrus segments up to 15 (rarely 16). 



2'. Pi with 12-28 (rarely less than 15) rather short segments, the longest about 

 twice as long as broad, often with markedly flared and spinous distal ends; 

 opposing .spine of cirri sometimes reduced (Fukien Province, China to south- 

 ern Japan; 0-180 meters) serrata (p. 163) 



i2. Pi with 8-13 segments, the longest about three times as long as wide, moderately 

 flared at the distal ends; opposing spine of cirri always acute (south-east 



Australia; 0-18 meters) loveni (p. 172) 



h'. Cirrus segments not more than 12 (Arabian Sea; 13 meters) arabica (p. 176) 



p. LTp to 18 cirrus segments, usually 14-16; from the Atlantic. 



