A MONOGRAPH OF THE EXISTING CRINOIDS 



103 



Dr. H. L. Clark, after studying 48 specimens of this species, 44 from Broome and 

 1 from Darwin collected by himself and 3 from the Capricorn Islands collected by 

 Livingstone and Boardman, wrote that this species is larger but more delicate than 

 Z. comata, with more arms and many more cirrus segments. He said that it is hard 

 to see why Gislen treated Z. elegans as merely a variety of Z. microdiscus, but from his 

 description he suspected that the individual he described as microdiscus was really a 

 large elegans with the maximum number of arms and cirrus segments. He said that 

 the large series of specimens from Broome show well the following differences between 

 the two species. In elegans the IIIBr series are 2, with few series beyond, and those 

 often 2; in microdiscus the IIIBr series are 4 (3+4), and the many subsequent series 

 are almost always 4 (3+4). The lowest pinnule in elegans is not nearly so flagellate 

 as in microdiscus, and is smaller in every way. The color in elegans is more varied 

 on the whole. 



The largest specimen studied by him had 51 arms about 130 mm. long, and the 

 cirri were XX, 45-56. A very fine specimen from Darwin has only 36 arms, but they 

 are nearly 1 50 mm. long ; the cirri have about 40 segments. The smallest specimen has 

 31 arms about 45 mm. long; all the IIIBr series are 2; the cirri have 36 segments. 

 The two specimens from Baudin Island are very small. 



The specimen from Amboina is a fine example of the species with 28 arms 160 

 mm. long. There are 8 IIBr 4(3+4) series, and 10 IIIBr 2 series. The cirri are 

 XXI, 35-44, 35-40 mm. long. 



The four specimens from Mermaid Strait have 35-80 arms. The IIBr series 

 are 4(3+4). The IIIBr and IVBr series are usually 2, more rarely 4(3+4). In cases 

 where IIIBr 4(3+4) series are developed they are usually external in relation to 

 the IBr series as in Himerometra, and there is also usually one more axillary on the 

 inner side of each IIBr series than on the outer, again as in Himerometra. Further- 

 more, the brachials are exceedingly short and discoidal as in Himerometra, so that at 

 a casual glance these specimens might very well be mistaken for examples of a species 

 of that genus. 



The form from Challenger station 190 was thus described by Carpenter: The 

 centrodorsal is a thick disk. The cirri are about XXV, 30-35. The fifth-eighth 

 segments are much longer than broad and those following diminish in length and 

 gradually develop a sharp forward-projecting spine, which decreases slightly in the 

 short terminal segments, but increases again on the penultimate as the opposing spme 

 to a strong recurved terminal claw. The radials are visible beyond the rim of the 

 centrodorsal. The IBr, are free laterally. The postradial series are quite free and 

 may divide four times. The IIBr series are 4(3+4). The IIIBr series and IVBr 

 series (when present) are usually 2. The 26 to nearly 40 arms are 40 to 45 mm. 

 long. They are composed of short, smooth, and obliquely quadrate brachials. 

 Syzygies occur between brachials 3+4, the next anywhere between the thirteenth 

 and sixty-first brachials, and thence at intervals of from 7 to 21 muscular articulations. 

 P D is long and tapering, with about 40 segments, of which the basal are tolerably 

 stout and the terminal are small. The second, and sometimes also the fourth, brachials 

 have similar but smaller pinnules, and those following decrease slowly in size, becom- 

 ing long and slender again toward the ends of the arms. The disk is 8 mm. in diam- 

 eter, much incised, with the interradial regions more or less covered with rather large 



