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 pedicellariae. On the other plates, i.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 papulae 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. Four 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 papulae. At irregular and wide intervals upon the disk are small, rather elongate, 

 pincer-formed pedicellariae with two narrow delicate jaws, sessile over the orifice of a 

 foramen in the plate. There are also a few much smaller valvate pedicellariae formed by 

 the slight modification of two juxtaposed granules. No pincer-formed pedicellariae 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 



