A MONOGRAPH OF THE EXISTING CRINOIDS 233 



ALTERNATIVE KEY TO THE SPECIES IN THE GENUS HETEROMETRA 



a 1 . Brachials distinctly wedge-shaped, the ends never quite parallel, those in the proximal portion 

 of the arms (except for the first few) very obliquely wedge-shaped and sometimes triangular. 



6 1 . Outer cirrus segments smooth dorsally, with or without a slight median carination, but 



never with dorsal spines or tubercles; 25-36 (usually about 30) cirrus segments; 16-26 

 arms 60-145 mm. long (from Philippines to Andaman Islands; 0-80 meters) 



quinduplicava (p. 245) 



6 2 . Outer cirrus segments bearing spines or tubercles dorsally. 



c 1 . Cirri tapering conspicuously distally so that the terminal third or fourth is only about 

 half as broad in lateral view as the proximal portion; cirri almost smooth, the last 10-15 

 segments with only slight and inconspicuous dorsal tubercles; distal cirrus segments 

 always longer than broad, varying from slightly longer than broad to twice as long as 

 broad. 



d 1 . Enlarged lower pinnules smooth, the segments with unmodified distal ends; Pj the 



largest and longest pinnule, 19 mm. long with 27 segments; cirri 30-33 mm. long with 



37-39 segments; 19 arms 120 mm. long (off western Java; 24 meters) .astyanax (p. 284) 



d 2 . Enlarged lower pinnules with the distal angles of the component segments slightly 



swollen and produced; P 2 the longest pinnule, 10.5 mm. long with 17 segments; 



cirri usually about 30 mm. long with usually 30-33 segments; 10-13 (usually 11-13) 



arms 90-120 mm. long (south of eastern Borneo; 82-88 meters) _propinqua (p. 277) 



c 2 . Cirri tapering not at all, or only very slightly, distally, the distal segments being never 



longer than broad and usually markedly broader than long, and bearing well developed 



dorsal processes. 



d 1 . Enlarged proximal pinnules slender and smooth, their basal segments without carinate 

 processes on the side toward the arm tip, and their outer segments with smooth and 

 unmodified distal ends. 



e 1 . Usually 20 arms, up to 150 mm. in length; enlarged lower pinnules very long and 

 slender, composed of about 20 segments; cirri with 23-33 (usually 25-30) segments 

 of which the outer bear long dorsal spines (Red Sea and eastward to Muscat; 0-18 



[?22] meters) savignii (p. 235) 



e 2 . Arms 38-48 in number, 105-115 mm. long; enlarged lower pinnules composed of 

 26-30 segments; cirri composed of 40-50 segments of which the outer bear promi- 

 nent, though not especially long, dorsal spines (Queensland and Aru Islands; 0-22 



[?36] meters) nematodon (p. 241) 



d 2 . Enlarged proximal pinnules with the basal segments carinate on the side toward the 

 arm tip, or with the outer segments bearing fine spines or other processes on the distal 

 ends. 

 e 1 . Enlarged proximal pinnules smooth, a few of the basal segments bearing carinate 



processes on the side toward the arm tip. 



/>. Longest cirri with not more than 30 segments; 15-18 arms 65-120 mm. long (Phil- 

 ippines to Singapore and Amboina; 0-36 meters) affinis (p. 285) 



f. Longest cirri with 30-40 segments. 



g l . Cirri with all the segments broader than long. 

 /i 1 . P 3 as large as, or larger than, P 2 . 



i 1 . Longest cirri with more than 40 segments, the outer with sharp dorsal spines; 

 arms up to 110 mm. in length (Maldive Islands and Ceylon and western 

 and northern coasts of Bay of Bengal as far as Akyab, Burma; 0-62 [?69] 



meters) reynaudi (p. 302) 



i'. Longest cirri with less than 40 segments, the outer with dorsal tubercles or 

 broad and usually blunt spines; larger, the arms 145-180 mm. long (Kei 

 Islands, Amboina and Singapore to Ceylon; 0-50 meters) .amboinae (p. 297) 

 h 1 . PS much smaller than P 2 



i 1 . Cirri with 32-36 segments; 14 arms about 160 mm. long; P a with 30 segments 



(Red Sea) ..ater (p. 311) 



208244 40 16 



