OPHIURANS OF UNITED STATES NATIONAL MUSEUM. 105 



OPHIOMITRELLA LEVIS, new species. 



Plate 10, figs. 1 and 6. 



Albatross station 2G66. May 5, 1886. Lat. 30° 47' 30" X.; long. 79° 49' W.- 

 270 fathoms; gy- s.; temp. 48.3° F. TSvo specimens. 

 Type.— Qui. No. 32298, U.S.N.M. 



Both specimens are small and the diameter of the disk does not exceed 4.5 to 5 

 mm.; neither of them is complete, and the arms are broken more or less near the 

 base. In the smaller one the disk is almost circular, whilst in the larger one it is 

 pentagonal, with rather excavated intcrradial spaces. 



The upper face of the disk is indented at the base of the arms; it shows five 

 pairs of protruding ribs, which succeed the very small radial shields and it offers in 

 its central region a depression which follows each radius to the base of the arms 

 between the radial shields. This face is covered with scales, which are very small, 

 rounded, and imbricated; each of them bears a small stump, wliich is very wide 

 at the base and becomes rapidly thinner, in the shape of a peduncle, becoming 

 again wider at the end, which carries a crown of from six to eight very small diverging 

 spinules very regularly arranged. These stumps are closely approximated to one 

 another, owing to the small size of the plates Mhich carry them; they form a very 

 regular and uniform covering over iha upper face of the disk. One perceives at the 

 end of each radial rib a very nan-ow little sliield, which is elongated, triangular, and 

 has a bare and finely granulous surface. 



The under face of the disk offers in the interradial spaces a covering similar to 

 that of the upper face, but ihc plates are less dense, and the stumps grow thinner 

 at the same time as the terminal spinules are fewer and shorter, but these stumps 

 extend up to the external edge of the mouth sliields. The genital sUts are plainly 

 visible. 



The mouth shields are middle-sizeil, triangular, M-ith an acute proximal angle 

 limited by two concave sides which join by sharp angles the distal side, which is very 

 strongly convex; they are scarcely wider than long. The adoral plates are very 

 much developed and remarkably wide, one and a half times longer than wide; they 

 are narrowed in their distal part, and they do not separate the mouth shield from 

 the first lateral bracliial plate. The oral plates are rather small, triangular, fairly 

 high. The oral papillse number three on each side; they are middle-sized and 

 conical, except the external papilla, which is rather obtuse; the odd terminal papilla 

 is wide, thick, and strong, often with a truncated apex: the surface of these papilla3 

 is very rough. It shoukl be noted that the distal sides of the mouth shields, of the 

 adoral plates, and of the first under brachial plate, build together the sides of a 

 regular pentagon, which is very conspicuous, has straight sides, and the angles of 

 which, corresponding to the distal sides of the mouth shields, are rounded. 



The arms are moniliform. The first two upper brachial plates are triangular, 

 with a rather acute proximal angle and a slightly convex distal side; they arc a little 

 wider than long, and their dorsal surface is somewhat protruding. From the third 

 plate upward this face becomes more convex at the same time as the proximal 

 angle gets rounded, and the distal side becomes Avider as well as more convex; the 

 plates thus ofl'ering some likeness with the campanuliform type. They are separated 

 from the base of the arm. 



