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 

 .styhform. 



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 

 diflerentiated 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 iVrafura Sea, off' the Ki Islands ; 

 lat. 5° 49' S., 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 t^-pe (PL XLL figs. 1-3), having deejier 

 re-entering 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. 

 fig. 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 aU 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 ivyville-thomsoni, Pentacriiius 

 maclearanus, or Pentacrinus alternicirrus. The respective lengths of these stems are 

 as follows : — (l) 3 8 "5 em. long, closed at the thirty-fifth node ; (2) 23 "5 cm. long, closed 



