92 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



In characters other than those mentioned this species resembles C. magnicirra and 

 C. rustica. 



Notes. One of the specimens from Mabahiss station 158 has 18 or 19 arms. The 

 cirri are about 40 mm. long with 51-55 segments; the eighth is a transition segment. 

 On the centrodorsal the pairs of columns of cirrus sockets are separated in the mid- 

 radial line by a broad and rather deeply concave bare area. The proximal edge of 

 the IBri, the proximal and distal edges of the IBr 2 , and the proximal edge of the IIBr! 

 are everted and armed with a few short coarse spines. 



The second specimen is similar, with 15+ arms. The longest cirri are 47 mm. 

 long, with 61-63 segments. The transition segment is the eighth. The pairs of cirrus 

 sockets are separated by a broad midraclial space. The dorsal pole of the centrodorsal 

 is papillose. 



Localities. Investigator station 124; Laccadive Islands (lat. 1047'45" N., long. 

 7240'20" E.); 1,265 meters; large water-worn fragments of reef coral [A. H. Clark. 

 1909, 1911, 1912, 1918, 1937] (2, U.S.N.M., 35582; I. M.). 



Mabahiss station 158; Maldive Islands (lat. 4 42'30" to 436'48" N., long. 

 7242'30" to 7248'54" E.); 914 meters; April 7 1934 [A. H. Clark, 1937] (2, B. M.; 

 Cairo Mus.). 



Geographical range. From the Maldive to the Laccadive Islands. 



Bafhyinetrical range. From 914 to 1,265 meters. 



History. This species was first described in 1909 under the name Crotalometra 

 sentifera from two specimens collected by the Royal Indian Marine Survey Steamer 

 Investigator at station 124 in the Laccadive Islands. In 1911 Crotalometra sentifera 

 was compared with the new species C. infelix. In 1912 this species was redescribed 

 and figured under the name of Thalassometra sentifera. In my memoir on the un- 

 stalked crinoids of the Siboga expedition published in 1918 sentifera was included in 

 the key to the species of Crotalometra, and the synonymy and range were given. In 1937 

 two additional specimens of Crotalometra sentifera were recorded and described that 

 had been dredged at station 158 in the Maldive area by His Egyptian Majesty's steamer 

 Mabahiss operating under the auspices of the John Murray Expedition to the Indian 

 Ocean, 1933-34. 



CROTALOMETRA RUSTICA A. H. Clark 



PLATE 11, FIGURES 35, 36; PLATE 18, FIGURE 58 

 [See also vol. 1, pt. 2, fig. 283, p. 215.] 



Crotalometra rustica A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 80 (description; 



Malay Archipelago, 30 fathoms), p. 147 (related to C. sentifera); Unstalked crinoids of the Siboga- 



Exped., 1918, p. 149 (in key; range; references); Ann. Mag. Nat. Hist., ser. 10, vol. 10, 



No. 58, October 1932, p. 378 (listed), p. 383 (off Madras; 600 fathoms; notes), pi. 15. 

 Crotalomelra infelix A. H. CLARK, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 550 (description; Albatross 



station 5317); Unstalked crinoids of the Si&o^a-Exped., 1918, p. 149 (identity). 

 Thalassometra rustica A. H. CLARK, Zool. Anz., vol. 39, No. 11/12, 1912, pp. 424, 425 (compared with 



marginalis) ; Crinoids of the Indian Ocean, 1912, p. 198 (synonymy; detailed description; locality), 



fig. 36, p. 199. 

 Thnlassomelra marginalis A. H. CLARK, Zool. Anz., vol. 39, No. 11/12, 1912, p. 424 (description; 



Siboga station 226) . 

 Thalassometra infelix A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 203 (synonymy; locality). 



