FEATURE IN DEEP-SEA OPHIURANS. 9 



by larger and more angular scales. Radial shields very small, wider than long, and touch- 

 ing. Genital openings large, extending from mouth-shield to margin of disk. Two 

 very short, peg-like arm-spines standing on outer edge of side arm-plates, but at nearly 

 a right angle to arm. One oval tentacle-scale. 



Color in alcohol, pale greenish gray ; arms lighter. 



" Challenger," Station 276, near Low Archipelago ; 2350 fathoms, 1 specimen. 



This solitary representative is highly interesting as almost the only deep-sea Ophiuran 

 found by the " Challenger " in the immense distance between the Sandwich Islands and 

 the S."W. coast of South America. 



Ophiacantha placentigera sp. nov. Plate II, figs. 20-22. 



Special marks. One very large, flat, tentacle-scale. Six cylindrical, tapering, nearly 

 smooth arm-spines. At inner point of each under arm-plate is a diamond-shaped raised 

 figure. 



Description of an individual. Diameter of disk 9.5 m.m. Width of arm, close to 

 disk without spines, 2 m.m. Five spaced mouth-papillae on each side of mouth angle, 

 the two outermost, large, squarish and flat, the three inner ones more pointed ; and the one 

 at the apex short and blunt. Mouth-shields broad triangular, with rounded corners, and 

 a blunt angle inward. Side mouth-shields long and large, nearly or quite meeting within, 

 where they taper; broad without where they join the side arm-plates and curve somewhat 

 round the mouth-shield. Under arm plates of a wide axe-shape, with a curve without, 

 reentering curves on the lateral sides, and an obtuse angle within. At the innermost 

 point on the median line, is a small raised figure in form of a transverse diamond. Side 

 arm-plates wide and thick, meeting fully below, just touching above. Upper arm-plates 

 broad diamond-shape, with outer and inner angles somewhat rounded, and with a central 

 longitudinal ridge ; length to breadth, 1.5 : 2. Disk flat and thick, closely set above with 

 short, thick, rounded, thorny stumps, four or five in 1 m.m. long, those in the centre being 

 smaller ; near the margin they are shorter ; and below they take the form of scattered 

 grains. Radial-shields small, of a short ovoid shape, widely separated and diverging 

 inward. Six long cylindrical, scarcely rough, slightly tapering arm-spines ; those above 

 and below shorter than the two middle ones, which are as long as two arm-joints. One 

 large, flat, wide, smooth, tooth-like tentacle-scale on the outer edge of the side arm-plate. 



Color in alcohol, very pale brown. 



"Challenger," Station 175, near Fiji Islands; 1350 fathoms; 1 specimen. 



Ophiopeza aequalis sp. nov. Plate II, figs. 23-25. 



Special marks. Disk uniformly covered, including radial shields, by a close granulation. 

 Ten flat crowded arm-spines nearly equal, except the lowest, which is larger. 



Description of an individual. Diameter of disk 25 m.m. Length of arm about 

 150 m.m. Width of same, close to disk, without spines, 5 m.m. Fourteen to seventeen 

 flattened, crowded mouth-papillae to each angle ; those within small and pointed ; the 

 two outermost on either side much the broadest. Mouth-shield short, rounded, heart- 

 shaped, with a blunt angle inward. Length to breadth, 4 : 4. Side mouth-shields very 

 small, occupying the outer lateral corners of the mouth-shield. Under arm-plates wider 



