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The unstalked crinoids of the Siboga-Expedition

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82

4. Heterometra affinis (Hartlaub).

HARTLAUB. Nova Acta der Ksl. Leop.-Carol. Deutschen Akad. der Naturforscher, vol. 58, 1891, N° 1, p. 25, pl. 1, fig. 14; pl. 2, figs. 18; 24 (not 21 as given in the reference to the plate) (Antedon affinis).

Stat. 99. 6°7'-5 N., I20°26'E. (Anchorage off North Ubian). 16—23 Metres. 1 Ex.

The specimen has fifteen arms about 70 mm. long; each IBr series bears on the right hand side (as viewed dorsally) a IIBr 4 (3 + 4).seriesi the two additional arms on the left anterior ray are as yet only 22 mm. in length, measuring from the axillary. The longest cirrus has 29 segments.

This appears to be a young individual just completing the adolescent autotomy.

Amphimetra A. H. Clark. Key to the Species of the Genus Amphimetra. 'gzh

a1 Cirri very stout, composed of very short subequal segments which are usually about four times as broad as long; the outer segments, which are relatively very slightly longer than the proximal, bear small sharp median spines b1 larger and stouter; cirri very large and stout, usually evenly curved throughout the entire length, never tapering distally, composed of 45—51 segments of which the distal half or two thirds bear dorsal spines; arms

from 150 mm. to 170 mm. long (Philippinelslands) spectabilis

b2 smaller and more delicate; cirri very stout basally, but usually tapering more or less distally, usually curved much more strongly in the distal than in the proximal half, composed of 34—37 segments of which nearly all bear dorsal spines; arms from 100 mm. to 115 mm. long (Maldives to the Sunda Islands, the Moluccas, the Philippines and

Singapore).. mollen

a2 Cirri more slender, more or less straight in the proximal half but strongly curved distally, composed of segments which are longer in the proximal portion than distally; the proximal segments are from twice as broad as long to as long as, or slightly longer than, broad

b1 the basal segments of the pinnules in the proximal fourth of the arm are strongly carinate; P4 is the largest and longest pinnule, slightly larger and longer than Ps, and twice as long as the distal pinnules; cirri XII, 30—33; arms 150 mm. long (Philippine Islands; ? North Borneo) . . , parilis

b2 the basal segments of the earlier pinnules are not carinate; the longest proximal pinnule is usually P3, more rarely Pg, which is very little, if any, longer than the distal pinnules

c1 cirri stout, not tapering distally; all of the cirrus segments are markedly broader than long