1078 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
end overlapping the broader or aboral end of the preceding plate. The marginal plates are a trifle 
larger than the abactinal, and all are moderately convex, the transverse as well as the longitudinal 
furrows between the plates being well marked. The skin which covers the plates bears relatively 
large flat granules which are very much larger in the center of the plate than about the borders and 
smallest immediately surrounding the papulae. The small granules are very irregular in shape, and 
not at all uniform in size. The larger are more roundish and very slightly imbricating. In one 
specimen they imbricate more noticeably and appear remarkably scale-like, the outer or free edges 
being subangular or obtusely pointed in many cases. Extending along the papular furrow between 
the superomarginal and adradial series of plates on either side of the ray is a row of peculiar and 
conspicuous 2-jawed pedicellarise, about 10 to 12 in number, sometimes less. There is but 1 pedicellaria 
to an area and it is large enough to be readily seen without magnification. Each consists of a double, 
broadly spatulate, specialized depression with a denticulate margin, into which fit, when open, the 
broad fan-shaped jaws, which bear 5 teeth or serrations at the edge, fitting nicely into 5 notches in 
the edge of the specialized depression. The figure will give the exact appearance of these. There 
are also 3 to 5 of the pedicellariae scattered on disk (abactinal) and usually 1 in each actinal inter- 
radial area, although this is occasionally absent in 1 or 2 interradii. One or 2 pedicellariae may be 
found at base of ray adjacent to that in the interradius. 
Adambulacral armature consists of 2 series of spinelets. Furrow series consists of small spinelets, 
the tips of which extend but a slight distance above the general granulation, and these tips are 
alternately larger and smaller although the difference is slight. When a portion of one side of the very 
narrow furrow is removed the spinelets are seen to be about twice as high as broad, with a rounded- 
truncate tip. The adoral is a shade narrower than the aboral . member, but it -is the latter that 
appears smaller (or more compressed) when viewed from the actinal surface. The difference in size 
is not constant, however, and is of little importance. Between 2 plates there is frequently a small 
granule fastened to the adoral edge of the adoral spinelet. On the actinal surface, spaced from the 
furrow spinelets a distance something less than their length, is a longitudinal series of larger ovoid 
tubercles which are not equidistantly placed, 3 to 6 of the furrow spinelets corresponding to 2 of the 
actinal. Small, rather scale-like granules are packed in the space between the 2 series of spinelets. 
The outer spinelets are bent away from the furrow. 
Madreporic bodies 2, small, situated rather nearer the margin than midway to center of disk. 
They are situated in neighboring interradii, but one is somewhat off the median interradial line. The 
bodies are flush with the general surface and the striations are few and coarse, either a smaller sinuous 
line, or V-, U-, and Y-shaped. Anal apertures apparently 2, surrounded by larger granules. 
Color in alcohol a bleached yellowish. 
Locality, station 3834, south coast of Molokai Island, on reefs; shore (4 specimens). Type no. 
21173, U. S. National Museum. 
This species is closely related to 0. robillardi a P. de Loriol, and more remotely to 0. germani & 
Perrier and 0. cribrarius c Ltitken. 
From robillardi it differs in having a coarser granulation, often scale-like, on the median portion of 
the plates, while that about the edges is finer; the pedicellariae are broader, with more denticulations, 
and the outer surface of each jaw is grooved near the free edge. The pedicellariae are single to a plate 
as in robillardi, but are situated in a papular area rather than on the plate. There is a slight inequality 
in the furrow spinelets, and the accessory granule, instead of being between the 2 spinelets of a plate 
as in robillardi is always found between 2 plates. The following synopsis' will serve to indicate the 
chief differences between the 4 related species. 
a. Papular pores 3 (2-4); plates more prominent. 
b. Arms usually flattened, granulation uniform, pedicellarise narrower, 3 or 4 denticulations on free 
edge; outer surfaces of jaw not grooved; pedicellarise on plates; furrow spinelets equal; acces- 
sory granules between the 2 spinelets of a plate robillardi 
bb. Arms usually cylindrical, granulation conspicuously larger in center of plate; jaws of pedicellarise 
nearly or quite twice as broad as high; 5 denticulations on free edge; pedicellarise on edge of 
papular areas, one to an area; furrow spinelets rather unequal; accessory granules between 
the adjacent spinelets of 2 adjacent plates lorioli 
(•Catalogue Raisonn6 des Echinoderm.es recueilles par M. V. de Robillard a l’Ue Maurice. <M6m. Soc. Physique et 
d’Hist. Nat. Gen&ve, t. xxix, no. 4, 1885, p. 24, pi. xv, figs. 1-5. 
b Revision des Stell6rides, 1875, p. 130. 
cVidensk, Meddel.,1871, p. 277. 
