A MONOGRAPH OF THE EXISTING CRINOIDS 121 



biol. und Hydrogr., 1915, pp. 224 ff. (detailed account of the distribution [Holothuria Bank 

 refers to Z. comata]); Unstalked crinoids of the Siboga-Exped., 1918, p. 60 (in key; range), p. 

 61 (synonymy; detailed description; station 273 [specimen from Holothuria Bank = Z. comata]), 

 p. 275 (listed), pi. 19, figs. 40, 41. — Gisl^n, Kungl. Fysiogr. Sallsk. Lund Handl., new ser., 

 vol. 45, No. 11, 1934, p. 21. 



Diagnostic features. — The cirri are short and rather stout, strongly recurved in 

 the distal half, with not more than 21 segments of which the longest are about as long 

 as broad. There are 11-21 arms 2 5-3 5 mm. in length. The division series are broad, 

 in close lateral contact, with straight lateral edges which are more or less flattened 

 against those of their neighbors. The color — white with numerous circular purple 

 spots on the division series and arm bases and in bandlike areas on the outer portions 

 of the arms — and the conspicuously banded white and purple cirri seem to be quite 

 distinctive. But it is always unsafe to rely too much on color when dealing with 

 comatulids. 



This species is much more likely to be confused with the young of certain species 

 of Heterometra than with the other species of Zygometra. It is easily distinguished 

 from these, however, by the syzygy between the elements of the IBr series. 



Description. — The centrodorsal is discoidal, thin, with a broad, flat, circular dorsal 

 pole 2.7 mm. in diameter. 



The cirri are XV, 18-19 (usually 18), 9 mm. long. The first segment is very 

 short, the second and third are about three times as broad as long, the fourth is about 

 twice as broad as long, and the fifth or sixth is about as long as broad. The next two 

 or three segments are similar and those following decrease very gradually in length so 

 that the outermost 10 or 11 are slightly broader than long. The sixth and following 

 segments bear prominent sharp dorsal spines. 



The radials are entirely concealed by the centrodorsal. The IBr] are very short 

 and bandlike, six or more times as broad as long, united to the IBr 2 by syzygy. The 

 IBr 2 (axillaries) are low triangular with the lateral angles slightly truncated, three 

 times as broad as long. There are 9 IIBr series present, 8 of which are 4 (3+4) and 

 one of which is 2. A single IIIBr series of two elements is developed internally on 

 one of the IIBr 4 (3+4) series. The IIBr series are broad like the IBr series with 

 straight lateral edges which are more or less flattened and almost or quite in apposition . 

 The lateral outer portions of the elements of the division series are roughened or very 

 finely papillose as in certain species of Mariametra. 



The 21 arms are 35 mm. long and are comparatively'short and/ather stout. The 

 first brachials are slightly wedge-shaped, three times as broad as the median length, 

 and are entirely united internally. The second brachials are much more obliquely 

 wedge-shaped, twice as broad as the external length. The first syzygial pair (com- 

 posed of brachials 3+4) is slightly longer internally than externally, and twice as 

 broad as long internally. The next three brachials are oblong, three to four times as 

 broad as long, and those following are wedge-shaped, twice as broad as long, becom- 

 ing as long as broad terminally. The brachials have rather strongly produced distal 

 edges. 



P D resembles P! and is composed of 20 segments. Pj is about 5 mm. long, rather 

 stout basally but in the distal half tapering to a slender tip, and is composed of 20 



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