MUSEUM OF COMPARATIVE ZOOLOGY. 39 



without, broader without than within, where they touch. First under arm- 

 plate small and three-sided, wider within than without : those beyond are one 

 half broader than long, with a curved outer side, and an irregular, more or less 

 truncated angle within. Side arm-plates unusually wide, but not much pro- 

 jecting, nearly meeting above and below. Upper arm-plates much wider than 

 long, three-sided, with a faintly curved outer side, and an angle, sometimes trun- 

 cated, within. Disk plentifully set with short, slender, cylindrical spines, and 

 'covered with well-rounded overlapping scales, which are large above (2 or 3 in 

 the length of 1 mm.), and more regular and much smaller below (4 or 5 in I 

 mm.). Radial shields sunken, rudely triangular, short and wide, separated by 

 a broad wedge of three or four large scales ; length to breadth 1.2 : 1. Four 

 cylindrical, tapering, blunt, rather stout arm-spines, the two upper ones largest 

 and somewhat longer than an arm-joint. One large, oval tentacle-scale. Color 

 in alcohol, pale straw. 



Station 174, 210-610 fathoms, 1 specimen. Station 171, 600 fathoms, 1 

 specimen. 



Ophiactis hirta sp. nov. 



Plate XIII. Figs. 365 - 367. 



Special Marks. — Disk finely scaled, and set with short, minute spines. 

 Radial shields small and pear-seed shaped. Four moderately stout tapering 

 arm-spines, the uppermost longest. Two or three minute mouth-papillee on 

 each side. Seven arms. 



Description of an Individual (Station 164"). — Diameter of disk 4.3 mm. 

 Length of arm about 14 mm. Width of arm near disk 1.2 mm. Two or 

 three small, narrow, scale-like mouth-papillse on either side of the very nar- 

 row mouth-angle ; and one, wide, flat, and pointed, at the apex ; this last may, 

 as in all similar cases, be considered the lowest tooth. Mouth-shields small, of a 

 much rounded diamond-shape ; sometimes nearly circular. Side mouth-shields 

 narrow, of nearly equal width, meeting within. Under arm-plates rather 

 small, as broad as long, bounded without by a strong curve, and within by 

 three sides of an octagon. Side arm-plates stout, projecting laterally in a well 

 marked spine-ridge, meeting neither above nor below. Upper arm-plates a 

 little broader than long, transverse oval, with the inner sides more or less 

 angular. Disk covered with coarse, thickened, irregular scales, those of the 

 under surface being sometimes wholly obscured by a thick skin ; those in the 

 centre are largest, but the primary plates are not readily distinguishable ; there 

 are small, peg-like spines scattered over the entire surface. There are seven 

 pairs of radial shields, which are small, sunken below the disk-surface, of a 

 blunt pear-seed shape, and separated by a rather wide wedge of three scales. 

 Four smooth, rounded, tapering, moderately stout arm-spines ; the upper one 

 longest; lengths to that of an under arm-plate, 1,.8, .7,. 7 : .5. One stout, oval 

 tentacle-scale. Color in alcohol, gray mottled with pale brown. 



Station 164", 400 fathoms, 1 specimen. 



