348 THE VOYAGE OF H.M.S. CHALLENGER. 
being about 100 mm. measured from the resting plane. Rays well produced, rather 
broad at the base and rather flat abactinally, tapering gradually to the extremity. The 
interbrachial ares very wide and well rounded. Actinal area plane along the rays, con- 
cave within the disk. 
The whole abactinal area is marked off by trabeculze into large ‘regular triangular 
papular areas, with a roundly conical tubercle at each angle. The tubercles fall into 
regular longitudinal lines, forming a median radial line and two parallel lines on each side. 
The tubercles or spinelets of the median line are not larger than the others, and all are 
subequal upon the disk, the primary radial ones being only the slightest shade larger than 
the others. The pentagon marked out by the primary radial tubercles is divided into 
smaller triangles with tubercles at their angles, which causes the tubercles to appear 
crowded there. From the base of the ray outward the tubercles diminish in size some- 
what, and there is considerable irregularity in their distance apart. At the tip of the ray 
they become robust, crowded, and more conical. Along the ray the papular areas are apt 
to be irregular in form. ‘There is a naked space devoid of tubercles and trabecule along 
the margin of the disk, and this is rounded and rather tumid, so that the supero-marginal 
tubercles are not normally visible along the margin of the disk and at the base of the 
rays when the starfish is viewed from above. The granulation consists of small granules 
with larger ones intermixed, the latter being more or less mammilliform, and often 
showing a tendency to form groups which simulate indistinct little rosettes. A few small 
elongate foraminal pedicellariz are present in each area, but are not numerous. The 
trabeculee are narrow, elevated, and well defined. The papule are numerous. The 
granulation mounts the bases of the tubercles, but never covers the tip, terminating with 
an abrupt line, which gives many of the tubercles rather an acorn-like appearance. 
The supero-marginal plates, which are twenty-seven in number from the median 
interradial line to the extremity, are small and each bears a tubercle, which is rounded in 
the disk area, but becomes more conical on the outer half of the ray, while the plate 
which bears it is also more or less mammillated, the base of the tubercle spreading out 
widely and occupying nearly the whole plate. 
The infero-marginal plates, which are twenty-nine or thirty in number, are confined 
entirely to the actinal surface, the supero-marginal plates forming the actual margin. 
Each plate bears a similar tubercle, which may frequently be doubled, and sometimes 
divided into three or four, all springing out of the one base. All the marginal tubercles 
have non-granulated tips like the tubercles on the abactinal surface. Elongate foraminal 
pedicellarize are rather numerous on the infero-marginal plates, and are also present on 
the superior series. In the space between the supero-marginal and infero-marginal 
tubercles are a number of larger “ granules,” which bear a striking resemblance to paxillee 
in consequence of having a circlet of smaller granules round their margin surrounding a 
central granule. 
