330 THE VOYAGE OF H.M.S. CHALLENGER, 
from its form might easily at first sight be mistaken for a teat-like or subpapilliform 
tubercule. They are covered with skin, and usually stand near the middle of the plate, 
and exhibit no definite posture as regards the orientation of the median cleft. Occasionally 
two are present on a plate. There are also on the plate small indistinct widely spaced 
granules, whilst on the two innermost plates there are several larger granules, nearly as 
large as the pedicellari. On the other plates, 7.e., in the inner part of the interradial area, 
there is occasionally a small pedicellaria of similar form to those just described, but much 
less conspicuous, and they bear similar small widely spaced granules which are larger on 
the plates on the inner part of the area than those near the margin. 
The abactinal area of the disk and rays within the boundary of the supero-marginal 
plates is covered with small, thin, hexagonal plates, the whole being overlaid with a 
continuous layer of membrane and beset with numerous, coarse, rather well-spaced 
granules. It is only possible to distinguish here and there the sutures of the plates 
through the membrane, although the general indication of the plates is to a certain extent 
given by the presence of small papule which have passage at the angles of the plates, and 
thus mark out their form more or less clearly. When, however, the starfish is held up to 
a strong, concentrated light, the hexagonal form of the plates and their pavement-like 
character is well seen. A regular series extends along the median interradial line, and the 
rest are arranged parallel to this. The median series does not reach quite to the tip, but 
terminates at a short distance before this is reached, the two or three terminal supero- 
marginal plates touching (meeting) the corresponding plates from the opposite side. The 
other series do not extend so far as the median series, and die out one after the other in 
conformity with the taper of the ray. In the radial areas of the disk there is on each 
side of the median series a series of smaller plates, which extend but a very short distance 
beyond the base of the ray, where they die out gradually. The plates of the series 
external to this short series of small plates are as large as those of the median series, and 
are contingent with them along the ray after the disappearance of the small intermediate 
series. our or five series of plates, inclusive of the small series, may be counted on each 
side of the median series at the base of the ray. The plates on each side of the median 
interradial line are comparatively large in relation to their neighbours and are not separated 
by papulz. At irrecular and wide intervals upon the disk are small, rather elongate, 
pincer-formed pedicellaris with two narrow delicate jaws, sessile over the orifice of a 
foramen in the plate. There are also a few much smaller valvate pedicellarize formed by 
the slight modification of two juxtaposed granules. No pincer-formed pedicellarie are 
present on the large plates in the median interradial area. 
The anal aperture is subcentral. 
The madreporiform body, which is large, circular, and flat superficially, is situated rather 
nearer the centre of the disk than midway on the interradial line. The striations, which 
are very fine and numerous, have the appearance of radiating from the centre to the 
