MONOGRAPH OF JAPANESE OrHIUKOIDEA. I95 



h-Two, or sometimes three, distal oral papiUœ on either side, 



besides an additional one, which lies deep within the oral slit. 

 c— Three arm spines, subeqnal, or the middle one slightly longer than 

 the other two ; disk distinctly squamated both above and below, 

 with very prominent primaries ; radial shields large, rather wide, 

 each pair being separated from each other by a row of usually 



three large scales; ventral arm plates wider than long Jcorcœ. 



ce— Four arm spines, of which the lowest one is the longest and 

 the third from below the shortest; disk distinctly squamated above, 

 but co^'ered with fine granule-like scales below ; the primaries are 

 indistinct in larger specimens ; radial shields long and very narrow, 

 slightly divergent; outer end of each genital plate, just distal to 

 the radial shield, bearing a projection, which is thorny at the tip ; 



ventral arm plates longer than wide digitula. 



hh-^mg\e distal oral papilla on either side, besides an additional one, 



which lies more or less deep within the oral slit. 

 d — Four arm spines. 



e— Disk squamated both above and below. 



/—Disk scales very fine and thin ; radial shields long and narrow, 

 about thrice as long as wide, separated from each other ; adorai 

 shields not meeting with each other; arm spines subeqaul . . .hellis. 

 #— Disk scales rather coarse and thick, some of them projecting like a 

 hemisphere, so that the surface of the disk is very rough; radial 

 shields not very long, about twice as long as wide, separated from 

 each other; adorai shields meeting with each other in the inter- 

 radial line ; the uppermost and the lowest arm spines distinctly 



longer than the middle two trachydwca. 



€e-Disk squamated above, but naked below ; radial shields partially 

 joined in pairs ; adorai shields meeting with each other in the 

 interradial line; middle two of the four arm spines stouter and 



blunter than the uppermost and lowest microdiscus. 



dd—Fixe to seven arm spines; disk naked at least below. 



