82 



Ophiothrix virgata, Lyman. 



Special marl:^. Disc beset witli slender spines. Arms twelve times 

 as long as the diameter of the disc ; along their upper side, a clear 

 white line, bordered by a narrow blue one on each side. 



Description of a specimen. Diameter of disc, 6 miUim. Width of 

 arm, without spines, 1 millim. Length of arm, 75 millim. Tooth- 

 papillae 13, in horizontal rows of two or three; lowest ones the 

 smallest. Teeth four, very thick and stout, standing close together. 

 Mouth-shields heart-shaped, with a pretty distinct point inward, 

 broader than long ; length to breadth, .8:1. Side mouth-shields meet- 

 ing nearly, or quite, within. Under arm-plates four-sided, with 

 cleanly rounded corners ; length to breadth (12th plate), .6 : .7. Upper 

 arm-plates, wider without than within, outer side cleanly curved, lateral 

 sides a little re-enteringly curved and sloping towards the centre of the 

 arm; length to breadth (8th plate), .7:1. Disc above and below 

 pretty closely covered with short, tapering, thorny spines, the longest 

 1 millim. in length, which nearly obscure the scaling of the disc, 

 which may be distinguished through the skin. Radial shields nearly 

 naked, separated by a single line of spiny scales ; length to breadth, 

 1.8 : 1.2. Arm-spines six, slender, not swelled at the point, upper one 

 commonly longest; lengths to that of under arm-plate, 1.7, 1.7, 1.4, 

 .9, .6, .5 : .6. Tentacle-scales very distinct, round. Color, in alcohol, 

 above, pale blue on the disc ; the radial shields with a speck of white 

 at their outer ends ; arms obscurely banded with paler and darker 

 blue ; along the middle of the arm a clear line of white bounded by 

 a narrow blue line on each side ; below, interbrachial spaces pale 

 blue ; the rest nearly white. 



Ophiothrix spongicola must be quite near this species, but its arms 

 are much shorter, and the pattern of color different. Kingsmill 

 Islands. 



Ophiothrix demessa, Lyman. 



Special marks. Upper surface of disc, with radial shields closely 

 covered with minute spines, bearing a crown of thorns. Arms about 

 nine times as long as the diameter of the disc. Little thorny spines 

 on the upper arm-plates. 



Description of a specimen. Diameter of disc, 10.5 millim. Width 

 of arm, without spines, 1.9 millim. Length of arm, 97 millim. 

 Tooth-papillae fifteen, unusually stout, standing on a level with each 

 other, arranged in horizontal rows of from two to four, according to 

 size ; upper ones stoutest. Teeth four, thick, stout, standing well 

 apart. Mouth-shields much broader than long, oval, with a faint 

 point inward ; length to breadth, .7 : 1.1. Side mouth-shields very 

 small and narrow ; not meeting within. Under arm-plates small, 

 squarish, with rounded corners, rather broader without than within ; 



