A MONOGRAPH OF THE EXISTING CRINOIDS 91 



ICONOMETRA SPECIOSA A. H. Clark 



PLATE 10, FIGURES 48, 49 



Iconomctra speciosa A. H. CLARK, Journ. Linn. Soc. (Zool.), vol. 36, No. 249, 1929, pp. 635, 643 

 (description; off Cape Padaran), pi. 40, figs. 1, 2. GISLEN, Kungl. Fysiogr. Sallsk. Lund 

 Forh., vol. 7, No. 1, 1936, p. 2 (southern Annam), p. 5 (French Indo-China), p. 6 (range). 



Iconometra spinosa PRESTON, Zool. Rec. for 1929, 1930, p. 28 Echin. (editorial error). 



Diagnostic features. The arms are about 20 in number, and are 75 mm. long; 

 the cirri are XL, 20-23, 13 mm. long. 



Description. The centrodorsal is hemispherical, slightly flattened, 3.5 mm. broad 

 at the base. The dorsal pole, which is about 1 mm. broad, is studded with small 

 scattered tubercles. The cirrus sockets are arranged in three rows and a partial 

 fourth row. 



The cirri are about XL, 20-23, about 13 mm. long. The first segment is very 

 short, the second is twice as broad as long, and those following gradually increase in 

 length so that the fifth or sixth and those succeeding are very nearly as long as broad, 

 becoming terminally quite as long as broad. The cirri of the peripheral row are all 

 lacking; in these probably all the segments are broader than long. On the third or 

 fourth segment the proximal end is thickened dorsally. On the segment succeeding 

 this thickening rises into a transverse ridge with a very finely dentate crest which 

 is convex when the segment is viewed from the end. On the segments following this 

 crest becomes straight. Distally the crest becomes gradually shorter, but the process 

 remains as a proximal transverse ridge as far as the antepenultimate segment. The 

 opposing spine is prominent, higher than the transverse ridge on the preceding seg- 

 ment, conical or with a chisel-shaped transversely elongated edge, median or situated 

 hi the proximal portion of the penultimate segment, and inclined more or less prox- 

 imally. The cirri are rather stout, and are of uniform width throughout. 



The distal borders of the radials are just visible beyond the run of the centrodorsal. 

 They are narrowly thickened, or are provided with a continuous row of fine beadlike 

 tubercles. The IBri are short, four or five times as broad as long, somewhat higher 

 in the median line than laterally. The lateral borders are in contact basally, but 

 from the point of contact the sides of each IBrj converge strongly. The proximal 

 borders of the IB^ are everted and slightly thickened, or are provided with a contin- 

 uous row of small beadlike tubercles. The outer portions of the distal border, and 

 the lateral borders, are slightly everted. The IBr 2 (axillarics) are sharply triangular, 

 twice as broad as long. The proximal border is straight. The lateral angles arc just 

 in contact with those of their neighbors, and therefore extend beyond the truncated 

 anterolateral angles of the IBri. Except in the middle of the proximal edge, the 

 borders all around are everted. A prominent high and narrow synarthrial tubercle is 

 present on the articulation between the elements of the IBr series. The IIBr and 

 IIIBr series are 2, and resemble the IBr series. Only a single externally developed 

 IIIBr series is present. 



The arms are apparently 21 in number, and are about 75 mm. in length. The 

 first brachials are wedge-shaped, twice as long exteriorly as ulteriorly, and between 

 three and four tunes as broad as long hi the median line. The outer border is pro- 



