Clark — Tivo New Astroradiate Echinoderms. 173 



in the two upper rows on the inferoniarginals, which have brown bases; 

 beneath, straw yellow. 



Type.— Cat. No. 36,948, U. S. N. M., from "Albatross" Station 2797, 

 off the coast of Colombia, in 33 fathoms. 



Ophiosteira koehleri, new species. 



The disk is 5 mm. in diameter; the arms are very slender, evenly tap- 

 ering, 40 mm. long. 



The plates of the disk are few, large, greatly swollen; the radial areas 

 are strongly elevated, the narrowly triangular interradial areas strongly 

 depressed. 



The dorsal surface of the disk is overlaid by a thin semi-transparent 

 membrane with an approximately plane surface which conceals the under- 

 lying plates. In drying this membrane may cling tightly to the surface 

 of the plates, or it may stretch, drum-head like, between the more elevated 

 plates more or less concealing the others from view. 



The radial shields are large, rather narrow, greatly swollen, extending 

 from the base of the arms half way to the center of the disk, in apposition 

 for the distal half. 



An oval, greatly swollen, plate occupies the area between the inner 

 halves of adjacent radial shields; just within this are two or three similar, 

 but much smaller, oval plates, radially elongated, beyond which is the 

 nearly circular primary radial plate, which is of about the same area as 

 the plate between the inner halves of the radial shields of each pair, and 

 also as the rounded-pentagonal central plate. The radial primary plates 

 are separated from this last by a ring of small transversely oval plates, 

 and from each other, in their basal halves, by similar, but slightly larger, 

 plates. 



The triangular interradial areas, embracing on the border of the disk 

 the region between the radial shields as a base, and extending inward to 

 an apex between the primary radial plates, are occupied by a large kidney- 

 shaped, much swollen, plate situated on the border of the disk between 

 the radial shields, in area about equal to the plate between the distal 

 halves of the radial shields of each pair ; beyond this on either side is a 

 small hemispherical plate attached immediately below the radial shields, 

 just within which is a transversely oval, much smaller, though similar, 

 plate, bridging the gap between the inner ends of the radial shields, and 

 within this one or two smaller plates. 



In lateral view the interradial areas of the disk are seen to be occupied 

 by about six irregularly rounded swollen plates. Along the genital slit 

 there are about ten prominent well separated conical papilla?, distal to 

 which are two or three larger, more robust, papilla?, forming the rudimen- 

 tary arm comb which is entirely hidden from dorsal view by the extension 

 over it of the produced distal border of the radial shields. 



The oral shields have a broadly heart-shaped inner portion, occupying 

 about two-thirds of their radial length, and a smaller transversely oval 

 outer portion, the two portions separated by deep lateral notches. 



