RECENT OPHIURANS. 201 



margin broadly curved. Interbrachial areas below, finely scaled but without 

 granules. Genital slits long reaching nearly to disk-margin. Oral shields, 

 large, oval, a trifle longer than wide. Adoral plates small, triangular, barely 

 meeting within, longer than their outer (basal) width. Oral plates rather large, 

 each with 4 small flat oral papillae on the margin; of these papillae the middle 

 2 are smaller than the most proximal or the distalmost ; the last is largest of all. 

 There are 3 or 4 teeth but no true tooth-papillae. First under arm-plate very 

 small, quadi'ilateral, narrowest distally; succeeding plates longer than wide, 

 broadly in contact throughout, quadrilateral, narrowest proximally, with distal 

 margin curved. Side arm-plates small, not projecting nor meeting either above 

 or below; each carries four smooth, slender, tapering spines, of which the lowest 

 is shortest, the uppermost longest; the latter equals two arm-joints. Tentacle- 

 scale large, single, flat. Color: — disk-scales, gray; granules, brownish; spine- 

 lets, whitish; arms, dull purplish, banded with a very light shade, each band 

 about 2 joints wide, each interval about 3 joints; nearly all the arm-plates, 

 both upper and under, have a whitish spot at the middle of the distal end and a 

 large one proximally (either spot may be wanting); arm-spines and tentacle- 

 scales, pale. 



HoLOTYPE (M. C. Z. 3700). Hawaii: Hilo. Carnegie Exp., 1913. H. L. 

 Clark coll. 



This pretty little brittle-star was collected on the under side of a stone, on 

 a shore-reef south of Hilo, Dec. 10, 1913. It had the general appearance of an 

 Ophiactis, quite in accord with its environment, but it is evidently an ophia- 

 canthid. No doubt it is young but there is no reason for supposing the adult 

 is essentially different. It is well characterized by the number and arrangement 

 of the oral papillae and the form of the arm-plates. 



247. 0. MARSUPIALIS L\-man, 1875. Illus. cat. M. C. Z., no. 8, pt. 2, p. 1.3, pi. 1, f. 9, 10. 



HoLOTYPE and 1 paratype. Juan Fernandez, 240 fms. 



248. O. MESEMBRIA, sp. nov. (^eaiitifipia. the south). 



0-phiacanlha meridiormlis Koehler, 1914. Bull. 84 U. S. N. M., p. 91, pi. 9, f. 1, 2. nnn Lyman, 

 1869. Bull. M. C. Z., 1, p. .324. 



Disk, 5 mm. in diameter; arms 30-35 mm. long. In general very similar 

 to 0. pentacrinus Liitken but with disk more distinctly circular and covered 

 with thorny spinules rather than with thorn-crowned stumps. The important 

 distinction is found in the outer (distalmost) oral papilla which is broad and 

 flat in mesembria while in pentacrinus it is not diff'erent from its two fellows. 

 Color of dry and alcoholic material, nearly white. 



