A MONOGRAPH OF THE EXISTING CRINOIDS 207 



each other, those of adjacent radial areas separated by a narrow and irregular bare 

 area which may show a slight narrow rounded ridge in the center. There are three 

 cirrus sockets to a column. 



The cirri are XXX, 18-19, 35 mm. long, short and stout. The first segment is 

 very short, the second is about twice as broad as long, and those following gradually 

 increase in length so that the fifth is about as long as the median or distal diameter. 

 The remaining segments are all about half again as long as the proximal width. The 

 last five segments decrease rather rapidly in diameter so that the penultimate segment 

 and the terminal claw are very small. After the first four segments the cirri become 

 rather strongly compressed laterally; the ends of the segments are slightly swollen and 

 prominent. 



The ends of the basal rays are visible as small tubercles in the angles of the calyx. 



The radials are entirely concealed. The IBr! are almost concealed, but their 

 distal portion, which is more or less irregular and tubercular, is visible as a narrow 

 band just below the axillaries. 



The 10 arms are about 210 mm. long. The diameter of the animal at the level of 

 the seventh brachial is 22 mm. The proximal brachials have the same prominent 

 median tubercles as those of C. robusta, but they are pointed instead of being rounded 

 as in that species, and they lean somewhat anteriorly so that they appear as broad 

 stout overlapping spines. Instead of being perfectly smooth as in C. robusta, the distal 

 borders of these earlier brachials are thickened and produced. These thickened and 

 produced borders after the first six or seven brachials bear, in addition to the large 

 broad median spine the base of which runs backward along the whole median line of 

 the dorsal surface of the segment, one or two smaller and more pointed spines between 

 the median spine and the lateral border which do not involve the dorsal surface of the 

 segments. 



Localities— Siboga station 297; East Timor Sea (lat. 10°39' S., long. 123°40' E.); 

 520 meters; soft gray mud with brown upper layer; January 27, 1900 [F. W. Clarke 

 and W. C. Wheeler, 1915, 1917, 1922; A. H. Clark, 1916, 1918; Gislen, 1927] (1, Am- 

 sterdam Mus.). 



Albatross station 5656; Gulf of Boni, Celebes; Olang Point bearing N. 67° W., 

 14.5 miles distant (lat, 3°17'40" S., long. 120°36'45" E.) ; 871 meters; bottom tempera- 

 ture 5.11° C; gray mud; December 19, 1909 [A. H. Clark, 1918] (1, U.S.N.M., 35702). 



Geographical range. — From Celebes to the East Timor Sea. 



Bathymetrical range. — From 520 to 871 meters. 



Thermal range. — One record, 5.11° C. 



History. — This species was first mentioned as Chlorometra rugosa (nomen nudum) 

 by Prof. Frank Wigglesworth Clarke and Dr. W. C. Wheeler in an analysis of the 

 inorganic constituents of the skeleton published in 1915 and republished in 1917 and 

 1922. The fragments analyzed came from the type specimen dredged at Siboga 

 station 297. On the establishment of the genus Chondrometra in 1916 Chondrometra 

 rugosa (nomen nudum) was listed among the constituent species. Chondrometra 

 rugosa was described and figured in my memoir on the unstalked crinoids of the Siboga 

 Expedition published in 1918 on the basis of a specimen from station 297, and at the 

 same time another specimen was recorded from Albatross station 5656; Clarke and 



