A MONOGRAPH OF THE EXISTING CRINOIDS 373 



COM ATULA MICRASTER A. H. Clark 



Plate 41, Figures 112, 113, 115-124 



[See also vol. 1, pt. 1, fig. 39 (syzygy), <p. 75; pt. 2, figs. 15, 16 (centrodorsal and radials), p. 15; 

 fig. 265 (arm and pinnules), p. 207; figs. 410, 411 (pinnule tip), p. 255; figs. 626-628 (comb), 

 p. 319; fig. 693 (disk), p. 341] 



Comatula micrasler A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 143 (description; 

 Andaman Is., 60 fathoms); Memoirs Australian Mus., vol. 4, 1911, p. 742 (10-armed species 

 related to C. etheridgei) ; p. 745 (never more than 10 arms); Crinoids of the Indian Ocean, 

 1912, p. 81 (synonymy; detailed description; localities); fig. 2, p. 82; p. 315 (additional locali- 

 ties); Unstalked Crinoids of the Siboga Exped., 1918, p. 271 (listed); Smiths. Miscell. Coll., 

 vol. 72, No. 7, 1921, pi. 1, fig. 12 (disk). 



Comatula (Comatula) micrasler A. H. CLARK, Unstalked Crinoids of the Siboga Exped., 1918, p. 27 

 (in key; range; references; station 33). 



Diagnostic features. The absence of cirri and the small size, the arms not 

 exceeding 65 mm. in length, readily distinguish this species from all the others in 

 the genus. 



Description. The centrodorsal is rounded pentagonal, with its dorsal surface 

 sunken to the level of the dorsal surface of the radials, or only very slightly above it. 



Cirri absent. 



The radials are short, trapezoidal, four or five times as broad as long. The 

 elements of the IBr series are united by syzygy (pseudosyzygy) forming a unit 

 which is about twice as broad as long. The IBri are almost entirely, or quite, united 

 laterally. The IBr 2 (axillaries) are free laterally. 



The 10 arms are from 50 to 65 mm. long, and with the pinnules resemble those 

 of C. pectinata. 



The color in alcohol is white or light purple. 



Notes. The difference in the length of the anterior and posterior arms is often 

 very great. In some specimens 6 only 4 of the 10 arms are provided with ambulacral 

 grooves. 



The specimen from Investigator station 387 has the arms about 45 mm. long. 

 There are 2 cirri still remaining on the centrodorsal, which is much reduced. 



The specimen from the Danish expedition to the Kei Islands station 83 is very 

 small. One of the two from station 82 has the arms up to 35 mm. long; the centro- 

 dorsal is not quite sunken to the level of the radial pentagon, and shows a few obsolete 

 cirrus sockets. The other specimen from station 82 is smaller, and the basal segments 

 of 5 more or less developed cirri are attached to the centrodorsal. 



The specimen from Siboga station 33 is typical. 



Localities. Investigator station 252; west of South Andaman Island (lat. 11 

 50' 30" N., long. 92 53' 00" E.); 110 meters; stones; April 10, 1899 [A. H. Clark, 

 1909, 1912] (45 U.S.N.M., 34935, 34939, 36194, 36245; I. M.). PI. 41, figs. 112, 113, 

 115-124. 



Investigator station 239; west of South Andaman Island (lat. 11 49' 30" N., 

 long. 92 55' 00" E.); 100 meters; sand and stones; April 14, 1898 [A. H. Clark, 1912] 

 (6, U.S.N.M., 34949; I. M.). 



See vol. 1, pt. 2, fig. 693, p. 341. 



