336 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLDME 1 



the gonad lies along the fourth to the tenth or eleventh segments. The other genital 

 pinnules are of between 23 and 30 segments and up to 16 mm. long; the gonads usually 

 lie along the third to eighth segments. All but the first two segments of the genital 

 pinnules are considerably longer than broad. Their distal edges are beset with fine 

 spines. 



The disk is naked. Sacculi are abundant. None of the specimens shows any trace 

 of an ambulacral skeleton. In the largest specimen there are many spicules, some 

 smooth and rodlike and others branched, in the tentacles of the distal segments of the 

 outer pinnules. 



Dr. John thought F. antarctica was distinguished from mawsoni by having con- 

 siderably longer oral and genital pinnules composed of a greater number of segments 

 and by the absence of strong spiny ridges on the distal edges of the lower brachials. 

 Also the cirri of the type specimens of antarctica are much heavier and longer than in 

 mawsoni. However in 1939 he decided that these were all characters of older specimens 

 of mawsoni and that the two could not be specifically distinguished. He found that, in 

 general, the younger specimens have the lower brachials more spiny but there is great 

 individual variation and an old specimen may be very spiny while a young one is nearly 

 smooth. 



Some very young specimens from B.A.N.Z.A.R.E. stations 40, 42 and 107 have 

 very strong, deeply-serrate, finlike processes standing out at right angles from the 

 distal edges of the IBrj and sometimes of the radials, strong groups of spines near the 

 lateral corners of the axillaries and enormous spinous processes arising from the distal 

 halves of the brachials. The various specimens have cirri composed of from 12 to 26 

 segments and PI of 11 to 19 segments. 



An atypical specimen from B.A.N.Z.A.R.E. station 107 differs considerably from 

 the rest, particularly in its cirri. These are of 26 to 33 segments and up to 36 mm. 

 long. The third segment is half again as long as broad ; the fourth to tenth are three to 

 four tunes as long as broad. Thereafter the segments slowly decrease in length, but 

 the most distal are twice as long as broad. The fourth to the tenth or twelfth are 

 slightly constricted in the midline, and the distal ends are wider than the proximal. 

 Beyond the twelfth or so the distal end increases in width so that it is considerably 

 wider than the proximal, but there is no dorsal spine. The cirrus tapers at the extrem- 

 ity; the opposing spine is rudimentary, the terminal claw very short and but little 

 curved. 



Another specimen from station 107 shows a curious abnormality. On one ray the 

 arms start normally but beyond the second brachials, each of which carries the usual 

 pinnule, they are fused together by a large syzygial pair, common to both arms. 

 Beyond it the ray splits again into two arms, each commencing with a syzygial pair, 

 the two pairs being closely apposed. The epizygal of each pah- carries a pinnule on 

 the outer side. 



The characters of the species can be summed up as follows. 



The centrodorsal varies from low flattened hemispherical or broadly truncated 

 conical in the larger examples, to conical with slightly swollen sides, usually about 

 two thirds to three quarters as high as wide. The cirri are XL-LXXX, with up to 33 

 segments. The arms in fully grown specimens vary from about 70 to 1 10 mm. in length. 

 PI has up to 50, but usually about 30, segments. P 2 is similar to P,. P 3 may be the 

 first genital pinnule but in larger specimens that is P 4 or even P 5 . 



