206 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The disk is concealed. The covering plates of the pinnule ambulacra are supported 

 on a limestone band which is not distinctly differentiated. The gonads are not pro- 

 tected by plates. The sacculi are variable, being moderately abundant on some 

 pinnules and rare on others. 



The color in alcohol is light brownish white. 



Note. An examination of the type specimen in the British Museum showed that 

 this is a small species with a narrow carination. The specimen appears to be a young 

 individual, and may prove to be a young example of C. robusta. 



Locality. Challenger station 214; off the Meangis Islands (lat. 433' N., long. 

 12706' E.); 914 meters; bottom temperature 5.44 C.; blue mud; February 10, 1875 

 [P. H. Carpenter, 1888; Hartlaub, 1895; A. H. Clark, 1907, 1908, 1909, 1911, 1912, 

 1913, 1916, 1918; Hamann, 1907] (1, B. M.). 



History. -Antedon aculeata was described and figured by Dr. P. H. Carpenter in 

 his report on the comatulids of the Challenger expedition published in 1888. Its 

 systematic and bathymetrical relationships were discussed by Dr. Clemens Hartlaub 

 in 1895, and in 1907 I compared it with a new species, Antedon (Chlorometra') garrettiana. 



In my first revision of the old genus Antedon published in 1907 aculeata was 

 referred to the new genus Charitometra, and in 1908 Charitometra aculeata was men- 

 tioned as the type of a nonoceanic group within the genus. On the establishment of the 

 new genus Chlorometra in 1909 aculeata was referred to it. In 1911 I compared Chloro- 

 metra aculeata with a new species, C. robusta, and in my memoir on the crinoids of the 

 Indian Ocean published in 1912 Chlorometra aculeata was listed and the synonymy and 

 range were given. In 1913 I published a short note on the type specimen in the 

 British Museum. In 1916 aculeata was again transferred to the new genus Chondro- 

 metra. In my memoir on the unstalked crinoids of the Siboga Expedition aculeata 

 was included in the key to the species of the genus Chondrometra and the synonymy 

 and range were given. 



CHONDROMETRA RUGOSA A. H. Clark 



[See vol. 1, pt. 1, fig. 99, p. 160.] 



Chloromelra rugosa F. W. CLARKE and WHEELER, U. S. Geol. Surv. Prof. Pap. 90-L, 1915, p. 194 

 (nomen nudum; inorganic constituents of the skeleton); Prof. Pap. 102, 1917, pp. 21 and following 

 (same); Prof. Pap. 124, 1922, p. 17 (same). 



Chondrometra rugosa A. H. CLARK, Journ. Washington Acad. Sci., vol. 6, No. 17, 1916, p. 608 (listed; 

 nomen nudum); Unstalked crinoids of the Siboga-Exped., 1918, p. 187 (in key; range), p. 188 

 (detailed description; station 297), fig. 8, pp. 188, 189 (Albatross station 5656), p. 275 (listed), 

 pp. 277, 278 (inorganic constituents of the skeleton). -GiSLEN, Vid. Medd. Dansk Nat. Foren. 

 K0benhavn, vol. 83, 1927, p. 33 (compared with Perissometra aranea). 



Diagnostic features . The centrodorsal is very large, truncated conical or more or 

 less columnar, with the cirrus sockets arranged in 10 regular columns, each radial 

 area with 2, more or less widely separated in the midradial line; the arms are 210 mm. 

 long; and the cirri are short, about one-sixth of the arm length, 35 mm. long with 

 18-19 segments. 



Description. The centrodorsal is very large, truncated conical, almost columnar, 

 9 mm. broad at the base, 4.5 mm. across the slightly convex dorsal pole, and 7 mm, 

 high interradially. The cirrus sockets are arranged in 10 regular columns, two to 

 each radial area; the columns in each radial area are almost or quite in contact with 



