416 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



oval or circular, flat or slightly convex scales, scarcely or not at all 

 overlapping, and 6 i^airs of radial shields, which are flat and very 

 small, but little larger than the largest of the disk scales; the two 

 radial shields of each pair are separated from each other or are 

 barely in contact distally. The interbrachial areas below are cov- 

 ered near the margin with thin, flat, rounded scales, like those of the 

 upper surface but much more evidently overlapping: toward the 

 mouth the scales are lacking and only a thin dark skin covers the 

 area near the oral shields; there are no granules or spinelets on the 

 disk, either above or below. 



Arms 6, rather short, less than 15 mm long, slender at tip. Upper 

 arm plates at base of arm at least twice as wide as long, very com- 

 pletely in contact but the proximal side is not quite so long as the 

 distal; the lateral margins are very evenly rounded, with no hint 

 of angles; near the tip of the arm the plates are much smaller and 

 more nearly separated from each other, the proximal side having 

 become a more or less truncated i)oint, the general form of the plate 

 being triangular. 



Oral shiekls small, somewhat elliptical, wider than long, not so 

 large as the first under arm plate. Adoral plates relatively very 

 large, narrow and truncate in front of the oral shield, where they are 

 in contact, much wider, and rounded, radially, where they meet and 

 almost overlap in front of the first under arm plate. It is possible 

 that these wide ends cover over and conceal the true first under arm 

 plate and that the apparent firet under arm plate is really the second. 

 Oral papilla single, located on the small narrow oral plate; it is 

 about twice as high as wide, flattened, and truncate or bluntly pointed 

 at tip; apparently it is easily knocked off for several appear to be 

 wanting; on only one jaw is the papilla present on both sides. Under 

 arm plates, except the apparent first, which is smallest and evidently 

 wider than long, squarish with rounded corners: the distal end is a 

 trifle wider than the proximal and its margin is very slightly con- 

 vex; lateral margins a very little concave; at the tip of the arm the 

 plates are much longer than wide: they are more or less fully in con- 

 tact throughout. Side arm plates low and small, meeting above near 

 tip of arm, but not below ; each carries a series of 4 arm spines, of 

 which the uppermost and lowest are smallest and subequal; the other 

 two are also subequal, but noticeably longer, about equaling the 

 width of the arm; all the spines are blunt and obviously thicker at 

 base than near tip; compared to the arm spines of 0. savignyi they 

 could be called slender. Tentacle scale single, flat, rounded, and rel- 

 atively large, as usual in the genus. 



Color of dry specimen very pale gray above, with a slight yellow- 

 ish tinge, cream white below ; a dusky blotch is visible on the upper 

 side of most of the larger arm spines. 



