230 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



port Heterometra was given as including gumduplieova (including clemens and anceps), 

 8amgnii, nematodo ariipinna (including brockii), producta, propinqua, crenulata 

 (including Comahda dubia von Graff, 1877, Antedon decipiens and A. irregularis Bell, 

 1884, Antedon bidentata von Gruff, 1884, Antedon dubia P. H. Carpenter, 1888, and 

 Orospedometra aliena A. II. Clark, 1909, with the exception of the 10-armed specimens 

 mentioned in the description of the Inst named), philiberti (including morienseni), flora, 

 qfrieana, schlegelii, singularis, pulchra, amboinae, joubini, gravieri, ater, madagascar- 

 idii, compta, aspera {=bengalensi$), bengalensis, and affinis. This inter- 

 pretation of the genus Heterometra has been accepted herein, but the key to the species 

 gh in in the Siboga report proving rather unsatisfactory, entirely new keys have been 

 prepared. 



KEY TO THE SPECIES IN THE GENUS HETEROMETRA 



a 1 . Outer cirrus segments smooth dorsally, or with a slight median keel, never with dorsal spines or 

 tubercles; 25-36 (usually about 30) cirrus segments; 16-26 arms 60-145 mm. long; division 

 m riis rather broad with slightly produced borders, though not in contact beyond the IBr 



axillary (from Philippines to Andaman Islands; 0-80 meters) quinduplicava (p. 245) 



a*. Outer cirrus segments bearing spines or tubercles dorsally. 



6'. Basal segments of the enlarged proximal pinnules without carinate processes on the side 



toward the arm tip. 



c 1 . Enlarged proximal pinnules smooth and slender, their component segments without lateral 



processes or spinous distal ends. 



(i 1 . Usually 20 arms, up to 125 mm. in length; enlarged lower pinnules very long and slender, 



composed of about 20 segments; cirri composed of 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) 



eP. 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 prominent, though 

 not j long, dorsal spines (Queensland and Am Islands; 0-22 [?36] meters) 



nematodon (p. 241) 

 r 1 . Segments of the enlarged proximal pinnules with variously modified distal ends so that the 

 profile of these pinnules is serrate. 

 <i l . Distal ends of the segments of the enlarged proximal pinnules with rounded processes, 

 but no spines; enlarged proximal pinnules sharply prismatic and usually much stiffened, 

 with the distal portion of the prismatic ridges on each segment produced into a rounded- 

 triangular process so that the profiles of these pinnules are very strongly serrate, with 

 conspicuous rounded teeth; division series and arm bases very rugged, the component 

 rles swollen dorsally, with prominent synarthrial and articular tubercles; 10-30 

 (usually between 11 and 22) arms 70-150 mm. long; cirri very variable, with 25-46 

 (usually between 30 and 45) segments (from Philippines to Andamans [possibly Mal- 

 dives], and southward to northern Australia; 0-111 meters) crenulata (p. 253) 



<P. Distal ends of the segments of the enlarged proximal pinnules with spines, either all 

 around or segregated at the prismatic angles. 

 e'. Enlarged proximal pinnules stout, composed of cylindrical or only very slightly pris- 

 matic segments which have everted and spinous distal ends, and usually larger on the 

 outer than on the inner arms of each ray; disk more or less extensively plated; 11-28 

 arms 50-140 mm. long; cirri with 16-38 (usually 30-35) segments (Amboina and 



Aru Islands; 0-20 meters) variipinna (p. 278) 



e>. Enlarged proximal pinnules slender, composed of strongly prismatic segments, which 



bear one or (usually) several spines at the distal prismatic angles, and the same size 



on all the arms; disk unplatcd; slender, with not more than 13 arms 50-100 mm. long. 



P. Cirri with 23-26 segments which from the tenth or eleventh onward are about as long 



as broad (Singapore and Maldive Islands; littoral) producta (p. 275) 



