314 THE VOYAGE OF II. M.S. CHALLENGER. 



Outward from the primary radial plate, the median radial Hue is occupied by a longi- 

 tudinal series of hexagonal paxillse, eight in number up to the base of the ray, the series 

 being then continued along the ray in the form of rectangular plates, regularly square 

 (excepting the first), against which the supero-marginal plates on each side of the ray 

 abut. This series of plates measures about 1 "5 mm. in breadth at the base of the ray, 

 and 1 mm. midway between the centre of the disk and the extremity of the ray. Parallel 

 to the median radial series of disk paxillse are other longitudinal series of similar, but 

 slightly smaller, hexagonal paxillse, which diminish slightly in size as they approach the 

 margin, their inner limit being the interradial line. The moderate-sized paxillas are 

 regularly hexagonal, with the margin beset with about twenty very short, subprismatic, 

 truncate, papilliform spinelets, and having about seven to ten small uniform semiglobular 

 granules rather widely spaced on the tabulum : the number varying a little according to 

 the size of the plate. It should be noted, however, that the plates which occupy the 

 depressed central area and its interradial extensions are more like plates than paxillse, 

 whilst those of the subiuflated radial areas of the disk are distinctly paxilliform. The 

 single series of small square plates which occupies the median abactinal line of the ray 

 are covered with small semiglobular granules precisely similar to those on the supero- 

 marginal plates, lineal marginal series being defined, especially on the lateral margins. 



The dorso-central plate is distinct and surrounded b} r a cycle of seven equal-sized 

 plates ; this in turn is succeeded by a series of more numerous but less regular plates, 

 amongst which the representatives of the under-basals must be sought. Some irregularity 

 masks the easy recognition of the latter, but where they do appear regularly placed they 

 are separated from the primary radial by a pair of plates. The basal plates appear to be 

 smaller and less conspicuous than the primary radials and are nearly at the same distance 

 from the centre. The madreporiform body is small and sunken, situated external to the 

 adjacent basal. The anal aperture is external to the dorso-central plate. 



No pedicellarise of any kind are present. 



Colour in alcohol, ashy white on the marginal plates and on the depressed area of 

 the disk ; whilst the inflated portion is of a very light brown shade, as are also the actinal 

 interradial areas. 



Locality. — Station 192. In the Arafura Sea, between the Ki Islands and Banda Islands. 

 September 26, 1874. Lat. 5° 49' 15" S., long. 132° 14' 15" E. Depth 140 fathoms. 

 Blue mud. Surface temperature 82° "0 Fahr. 



2. Paragonaster cylindratus, n. sp. (PI. LI. figs. 3 and 4 ; PI. LIII. figs. 3 and 4). 



Pays five. P = 51 mm. ; r= 12"5 mm. R>4 r. Breadth of the ray midway between 

 the centre and the extremity, 4"5 mm. 



Rays elongate, slender, narrow at the base, slightly tapering towards the extremity, 



