PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 547 



EUMORPHOMETRA AURORA John* 



Figure 30, f-A 



Eumorphometra aurora John, Discovery Reports, vol. 18, 1938, p. 123 (listed), p. 129 (range), p. 133 

 (in key), p. 152 (description; locality); text-fig. 6, a-d, p. 153; pi. 4, fig. 1; Rep. B.A.N.Z. Ant- 

 arctic Res. Exped. 1929-31, ser. B, vol. 4, pt. 6, 1939, p. 202 (B.A.N.Z. A. R.E. stations; 

 supplementary description; viviparity), fig. 3. 



Diagnostic features. — Wlien the arms are about 30 mm. long, there are about XL 

 cirri wdth up to 28 segments; the axillary is rliombic with, a large pro.ximal angle; the 

 divnsion scries are distinctly spinous around the edges; all the segments of P, except 

 the first one are longer than broad; the segments of the genital pinnules are not ex- 

 panded. 



Description. — The centrodorsal is rounded conical, 1.6 mm. in basal diameter and 

 1.4 mm. in vertical height, with the proximal border produced interradially into very 

 low and wide angles. The cirrus sockets are arranged in 10 columns with an addi- 

 tional socket between the proximal ends of the 10 columns in four radial ureas (see 

 fig. 30,y, p. 545). 



The cirri are about XI^I, 17-28. The peripheral cirri are up to 10 mm. in length, 

 with 27 to 28 segments. The apical cirri are about half as long, wath 17 to 19 segments. 

 The intermediate cirri are longer than the apical, with 21 to 23 segments. The first 

 three cirrus segments are broader than long, the fourth is as long as broad, and the 

 fifth to eighth or ninth are slightly longer than broad. All these have the distal end 

 slightly flaring, more strongly on the dorsal than on the ventral side, so that they are 

 a little wider distally than at the base. The more distal segments are about as long as 

 broad. Their dorsal sides are raised into low keeUike protuberances, highest near the 

 end of the segments, making them broader distally than proximallj\ The opposino- 

 spine is small and the terminal claw is short. 



The radials are nearly rectangular and fairly long, about half as long as broad. 

 In profUe the proximal half makes onlj- a slight angle with the dorsoventral axis, but 

 the distal half bends sharply outwards. The IBr, are not quite so long as the radials; 

 they are widely separated from each other and are not deeply- incised hy the a.xillaries. 

 The IBrj (a.xillaries) are slighth' longer than broad. 



The 10 arms are all broken; to the thirtieth braclual, approximatoh^ about three- 

 fourths of their full length, they are 20 mm. long. The fu-st brachials are about four 

 times as broad as the median lengtii, nearly as long exteriorly as broad, and widel_y 

 separated interiorly. The fifth to eighth brachials, between the first and second 

 syzygies, are nearly rectangular, about half again as broad as long. The brachials 

 between the second and third syzygics are wedge-shaped and longer than broad. The 

 more distal bracluals are longer on one side than on the other and arc slightly longer 

 than broad. The distal edges of the radials, elements of the IBr series, and first two 

 brachials are raised into very fine spines. The distal edges of all the brachials bej-ond 

 the first s^'zygy are faintly raised and produced into short spines. 



Syzj'gies occur between brachials 3+4, 9+10, and 14 + 15, and distally at inter- 

 vals of 3 muscular articulations. The length from the proximal edge of the IBr, to 

 the second syzygy is 7.0 mm. and the width at the first syzj-gy is 1.0 mm. 



►See also Addenda (p. 837) under 19G3. 



