6 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



neighbors; 10-20 arms (from southern Japan and the Hawaiian Islands to the Philip- 

 pines, Moluccas, and Kei Islands; 128-795 meters) Parametra (p. 64) 



e*. Cirri with 30-34 segments, of moderate length and moderately slender; division series 

 and arm bases very slightly convex dorsally but with a prominent sharp median 

 carinate process, everywhere in close lateral apposition ; lateral portion of the distal 

 border of the IBri, IIBri, and first brachials forming thin rounded anterior processes 

 which imbricate over the bases of the ossicles following; 13-15 arms (southwestern 



Japan; 188 meters) Lissometra (p. 88) 



6 2 . Arms dorsally rounded to the tips, never carinate; arms 10 or more in number, the IIBr series 

 when present 4(3+4) or 4(3 + 4) and 2, exceptionally by individual variation all 2; Pj 

 usually much enlarged, very stout and much broadened basally. 



e 1 . Cirri recurved at the tip or in the outer portion, the distal segments always carinate dorsally, 

 the carination usually raised into a prominent broad dorsal spine; opposing spine always 

 present. 

 d l . Division series and arm bases smooth and without spines, though the lateral edges may be 



everted and tubercular or serrate. 

 e 1 . Arms more than 15 (normally 20) in number; large and stout, with the arms 75-160 mm. 



long. 



/'. First syzygy following a IIBr 4(3 + 4) series between brachials 3 + 4; cirri in 10 definite 

 columns; cirri long and slender with more than 50 segments (from Formosa, the 

 Philippines, and the Malay Archipelago westward to the Maldive and Laccadive 



Islands and southeastern Africa; 55-1,595 [?2,047] meters) Crotalometra (p. 89) 



f 1 . First syzygy following a IIBr 4(3 + 4) series between brachials 2 + 3; [stouter, with 

 stouter and shorter cirri which have not more than 50 (30-50) segments; cirri in 15 

 indefinite columns (from Ascension Island to the Bay of Biscay; 768-1,420 meters). 



Koehlermetra (p. 100) 



e 2 . Arms not more than 15 (usually 10) in number. 



/'. Larger and stouter; 10 arms 90-150 mm. long; cirri 45-90 mm. long with 59-70 seg- 

 ments; IBr series and arm bases usually broadly rounded dorsally (from the Philip- 

 pines to Cerarn and the Kermadec Islands; 457-1,165 [?1,264] meters). 



Aglaometra (p. 107) 



P. Smaller and more slender; 10-14 (but rarely more than 10) arms 45-80 mm. long; cirri 

 17-50 mm. long with 30-66 segments; IBr series and arm bases carinate or subcari- 

 nate (from the Hawaiian Islands to Fiji, the Kermadec Islands, and southeastern 

 Australia westward to the Laccadive Sea; from the Canary Islands to Cape Carvoeiro, 



Portugal; 649 [?640]-2,468 meters) Stiremetra (p. 119) 



d 2 . Division series and arm bases more or less thickly beset with small spines or tubercles, at 



least laterally. 



e 1 . Arms 15-28 in number 90-180 mm. long; a more or less prominent middorsal keel on one 

 or both the elements of the division series and first two brachials (from western Timor 

 and the Kei Islands to the Philippines and Hawaiian Islands; 55-786 [7872] meters). 



Oceanometra (p. 137) 



e 1 . Arms less than 15 (usually 10) in number (from southern Japan, the western Aleutian, 

 Hawaiian, and Galapagos Islands, Panama, and the Kermadec Islands westward to 

 east Africa from Sokotra to the Crozet Islands; and from Tristan da Cunha and Ascension 



northward to the Canary Islands; 598-2,925 meters) Thalassometra (p. 151) 



c*. Cirri nearly straight, not recurved at the tip, tapering to a fine point, without dorsal spines or 

 carination and without an opposing spine, about half the length of the arms; 10 arms about 



180 mm. long (south of Lombok; 1,097 meters) Leilametra (p. 148) 



a'. Genital pinnules with the third-fifth segments greatly expanded, forming a roof over the gonads; 

 small and rather delicate with 10-22 (usually 15-20) arms 40-50 mm. long and 30-50 (usually 

 30-40) cirrus segments (Caribbean Sea; Cuba to St. Vincent and ?Grenada; 159-479 meters). 



Horaeometra (p. 185) 



