346 THE VOYAGE OF H.M.S. CHALLENGER. 
very massive, and generally somewhat cuboidal ; while the next few are narrower with 
flattened sides, but still of great thickness in a dorsoventral direction. The thickness 
gradually diminishes, and the outer part of the pinnule consists of moderately long, 
somewhat flattened joints, with the dorsal edges sharpened and projecting slightly forward 
over the bases of their successors. The distichal pinnules on the outer sides of the ray 
are longer and have somewhat larger joints than those borne by the radials. Beyond the 
distichal axillary, the size of the pinnules gradually decreases, the lower joints becoming 
at first prismatic and then flattened, but remaining distinctly larger than their successors 
for some little distance beyond the palmar axillaries. The later pinnules are short and 
styliform. 
The disk bears numerous small scaly plates, which are more thickly grouped on the | 
anal tube than elsewhere. Disk-ambulacra strongly but irregularly plated ; those of the 
arms distinctly above the arm-groove, and supported by regular bifid plates which become 
ciiferentiated on the pinnules into covering plates and ill defined side plates. 
Colour when fresh—the stems almost white, and the crowns light yellow or light 
reddish-orange (Moseley) ; in spirit, white or whitish-brown. 
Locality.—Station 192, September 26, 1874; in the Arafura Sea, off the Ki Islands ; 
lat. 5° 49’8., long. 132° 14’ E.; 140 fathoms ; blue mud. Seven specimens, and possibly 
more. 
Remarks. 
This species is readily distinguished from its nearest ally (Metacrinus 
cingulatus) by the characters of its stem-joints (Pl. XXXIX. figs. 3-11). They are 
much more sharply stellate than in that type (Pl. XLI. figs. 1-3), having deeper 
re-entermg angles; while the horizontal ridges on the sides of the internodal joints are 
generally not continuous, but interrupted at the angles, which are somewhat produced 
outwards (Pl. XXXIX. fig. 3). One specimen presents a curious variation in this 
respect. The horizontal ridges on the thicker joints are enlarged so as to have a some- 
what diamond shaped aspect, with more or less produced lateral angles (Pl. XXXIX. 
fiz, 11); and when this ridge is large it shows itself very plainly in a terminal view of 
the joint-face, outside the line of teeth (compare Pl, XXXIX, figs. 8 and 11). In this 
specimen too the downward extension of the basals over the upper stem-joints is 
especially well marked, and the supra-nodal joint is rather more hollowed to receive 
the cirrus-bases than it is in the type. The stems of five specimens all terminate below 
in a nodal joint. In two cases there appears to have been an attached portion of stem ~ 
beneath ; for the surface of this lowest nodal joint is comparatively fresh and its central 
canal visible; but in the other three stems this surface is somewhat worn, and I cannot 
make out the opening of the central canal, which appears to have been closed up, the 
animal living in a semi-free condition like Pentacrinus wyville-thomsoni, Pentacrinus 
maclearanus, or Pentacrinus alternicirrus. The respective lengths of these stems are 
as follows :—(1) 38°5 cm. long, closed at the thirty-fifth node; (2) 23°5 em. long, closed 
