122 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY 



Upper arm-spines not longest and not equalling joint. 

 Arra-spines numerous (8-13). 



Lowest arm-spine not noticeably longer than others and not 

 equalling joint. 

 Entire disc granulated, except radial shields; arm-pores 



present gorgonia 



Some other disc-plates bare, besides radial shields ; arm- 

 pores wanting {nfernalis 



Lowest arm-spine longest, exceeding joint angulata 



Arm-spines few (4-7). 



Arm-spines 4, lowest longest, with tips minutely spinous . . paudspina 

 Arm-spines 5-7 (rarely 8), tips not spinous. 



Radial shields small, widely separated, with 1-3 large, bare 



plates between ; arm-spines rarely 8 sphenisci 



Radial shields not separated bj' large bare plates. 



Arms 8-10 times disc-diameter ; arm-spines 6, lowest long- 

 est and equalling joint ; no arm-pores elegans 



Arms 4—6 times disc-diameter. 



Radial shields large and conspicuous ; distance between 

 two of a pair less than width of one. 

 Oral shields as wide as long ; arm-spines 7 ; arms 



slightly carinated megaloplax 



Oral shields decidedly longer than wide ; arm-spines 



6 ; arms strongly carinated nitens 



Radial shields small ; distance between two of a pair 

 greater than width of one. 

 Lowest arm-spine decidedly longest, equalling joint. 



Arm-spines 5; arm-pores present stabilis 



Arm-spines 6-7 ; arm-pores wanting petersi 



Arm-spines siibequal or lowest a trifle larger and 

 rather more than ^ arm-joint. 

 Arm-spines 5 ; upper arm-plates much wider than 



long ; arm-pores wanting capensis 



Arm-spines 6-7 ; upper arm-plates rounded, about 



as long as wide ; arm-pores present semicincta 



Arm-spines 7-8, upper ones longest, equalling or exceeding joint, 

 lowest much shorter, blunt ; under arm-plates much wider 



than long ; 2 pairs of arm-pores present honorata 



Radial shields more or less circular, minute (length commonly much 

 less than ^^ diameter of disc), but conspicuous because of their 

 very dark color ; more than 4 pairs of arm-pores are usually 

 visible in adult specimens ; lowest arm-spines conspicuously 

 longest. 

 Arm-spines 7-10, short, wide, flat, white- (or light-) tipped ; color 

 nearly uniformly dark ; arms banded with whitish or yellow- 

 ish, or not at all septemspmosa 



Arm-spines 7-9, as long as joint, not wide and flat, not white- 

 tipped j color light and dark ; arms banded with blackish . . macracantka 



