300 THE VOYAGE OF H.M.S. CHALLENGER 



diameter only very slightly greater than the longitudinal ; and in the outer two series the 

 difference is still smaller, whilst the respective diameters in the outermost series are almost 

 equal. The tabula of the three lateral series of paxillse bear fourteen to sixteen of the 

 marginal prismatic spinelets, and four to eight of the semiglobular granules in the enclosed 

 area. Most of the paxillse of the median series bear one of the large entrenched pedi- 

 cellariae similar to those above described, which extends across the major diameter of 

 the tabulum ; and here and there a paxilla of the lateral series is similarly provided. 



The interradial areas are nearly equilaterally triangular in outline, the base extending 

 along seven or eight of the supero-marginal plates in the interbrachial arc ; they are 

 covered with small subrhomboid plates compactly placed in lines parallel to the longi- 

 tudinal series of the radial areas, and are beset with small, uniform, semiglobular granules 

 similar to those on the supero-marginal plates ; some of these plates are also furnished 

 with pedicellarise, but they are few and far between. The converging lines of plates do 

 not form any abrupt indication of the median interradial line. 



The primary embryonic plates are clearly discernible, the primary radials and basal 

 plates being larger than the other paxillse ; a plate representing the under-basal is also to be 

 distinguished, and this is frequently separated from the primary radial by a pair of inter- 

 mediate plates; one or more series of intermediate plates intervene between the above- 

 mentioned primary plates and the dorso-central, which is a little larger. The anal 

 aperture lies external to this plate, opposite the postero-lateral interradium. The madre- 

 poriform body is small and slightly convex, and is placed external to the adjacent basal 

 plate, its position on the disk being about one-fifth of the distance from the centre to the 

 extreme margin. 



Colour in alcohol, yellowish white. 



Localities. — Station 204. Off Tablas Island, Philippine group. November 2, 1874. 

 Lat. 12° 43' 0" N., long. 122° 9' 0" E. Depth 100 to 115 fathoms. Green mud. 

 Surface temperature 84° '0 Fahr. 



Station 188. In the Arafura Sea, near the entrance to Torres Straits. September 

 10, 1874. Lat. 9° 59' 0" S., long. 139° 42' 0" E. Depth 28 fathoms. Green mud. 

 Surface temperature 78° "5 Fahr. 



Remarks. — Nymphaster symholicus is readily distinguished from Nymphaster pro- 

 tentus and its allies by the tabulate and paxilliform character of the radial abactinal 

 plates, by the presence of a medio-radial series of plates, which separate the two opposite 

 series of supero-marginal plates throughout the ray, and by the presence of large entrenched 

 pedicellarise of a remarkable form. 



la. Nymphaster symholicus, var. breviradiata, nov. 



A variety of Nymphaster symholicus occurs at Station 192. The form is of smaller 

 size, but the rays are comparatively a little wider and shorter. The paxillse of the 



