242 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The 20 arms are about 170 mm. long. The earlier brachials have slightly thick- 

 ened and more or less everted distal edges which as the brachials become triangular 

 change to simple overlapping distal ends. Traces of a rounded median tubercle may 

 be found at least as far as the end of the proximal third of the arm. 



The specimen from Siboga station 254 has 17 arms 130 mm. long. Of the IIBr 

 series five are 4(3+4) and two are 2. The cirri are rather slender, XXV, 14-16, 16 

 mm. long. 



One of the specimens from south of the Nicobar Islands, which were referred to G. 

 gorgonia with some hesitation, is very large but badly broken. The arms were appar- 

 ently 20 in number. One of the IIBr series is 2, the others being 4(3+4). The edges of 

 the ossicles of the division series and brachials are much less prominent than in the 

 specimen from Siboga station 294, while there is scarcely an indication of the median 

 tubercle beyond the lowest brachials. The cirri have 17-22 segments. With this there 

 is a very small specimen with 11 arms 50 mm. long, one IIBr 4(3 + 4) series being 

 developed. 



Localities Menado Bay, Celebes (lat. 131' N., long 12447' E.); 457 meters; 

 Captain Christiansen, Great Northern Telegraph Co., March 12, 1913 (4, C. M.). 



Siboga station 259; Kei Islands (lat. 529'12" S., long. 13252'30" E.) ; 487 meters; 

 coral sand and dead coral; December 16, 1899 [A. H. Clark, 1912, 1916, 1918, 1929; 

 Gisle"n, 1927, 1934] (2, U.S.N.M., E. 457; Amsterdam Mus.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortenseu; station 3; 245 meters; 

 sand; March 31, 1922 (7, U.S.N.M., E. 3203; C. M.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 8; 300 meters; 

 Aprils, 1922 (3, C. M.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 12; 320 meters; 

 sand; April 9, 1922 (5, U.S.N.M., E. 3198; C. M.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 56; 245 meters; 

 May 10, 1922 (2, U.S.N.M., E. 3167; C. M.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 58; 290 meters; 

 May 12, 1922 (5, U.S.N.M., E. 3165; C. M.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 59; 385 meters; 

 coral; May 12, 1922 (9, U.S.N.M., E. 3153; C. M.). 



Siboga station 254; East Arafura Sea, west of Taam Island (lat. 540' S., long 

 13226' E.); 310 meters; fine gray mud; December 10, 1899 [A. H. Clark, 1916, 1918; 

 Gislen, 1934] (1, U.S.N.M., E. 435). 



Siboga station 294; East Timor Sea (lat. 1012'12" S., long. 12427'18" E.); 73 

 meters; soft mud with very fine sand; January 23, 1900 [A. H. Clark, 1916, 1918] (1, 

 Amsterdam Mus.). 



South of the Nicobar Islands; 1,023 meters; cable repair ship Patrol, Eastern and 

 Associated Telegraph Co. [A. H. Clark, 1929] (2, B. M.). 



Geographical range. From northern Celebes southward to the Kei Islands, the 

 East Arafura Sea, and the East Timor Sea, and westward to the Nicobar Islands. 



History. Pachylometra crassa was originally described in 1912 from a specimen 

 from Siboga station 259. On the establishment of the genus Perissometra in 1916 

 crassa was transferred to it, and in the list of included species Perissometra gorgonia, a 

 nomen nudum, was given. In. my memoir on the unstalked crinoids of the Siboga 



