REPORT ON THE ASTEROIDEA. 497 



short, conical, placed on the margin of the lateral flange of the plate, and have saccular 

 investments. 



The actino-lateral spines, which are about forty-five in number on each side of the 

 furrow, are hidden in the thick fleshy tissue, and shallow channels or wrinkles traverse the 

 membrane between each spine, which give a fluted appearance to the interradial area on 

 the under side of the starfish. The longest spines are little more than the extreme breadth 

 of the ambulacral furrow, — a wide space, greater at the margin than the length of the 

 spines themselves, intervening in the interradial area between their extremities and those 

 of the spines of the neighbouring ray. The spines are directed slightly backward (i.e., 

 adorally in relation to the direction of the ray) ; and the series of those spines whose 

 extremities terminate in the ray-margin diminish very rapidly in length. 



Colour in alcohol, abactinal surface greyish white, tinged with purple on the radial 

 areas, the interradial areas and fringe being purplish grey. Actinal surface livid purple. 

 Ambulacral tube-feet yellowish grey. 



Locality. — Station 158. South of Australia, 1099 miles south-west of Cape Otway. 

 March 7, 1874. Lat. 50° 1' 0" S., long. 123° 4' 0" E. Depth 1800 fathoms. Globigerina 

 ooze. Bottom temperature 33° - 5 Fahr. ; surface temperature 45°'0 Fahr. 



Remarks.— This species, which is by far the largest Hymenaster known, is distinguished 

 by the single spinelet on the adambulacral plates, by the raised areas of the paxillse-crowns, 

 and by the small, numerous, and equidistantly spaced spiracula. In the specimen above 

 described, Sir Wyville Thomson l states that " there were one or two eggs in the pouch ; 

 but they were apparently abortive. It seemed that the brood had been lately discharged ; 

 for some oval depressions still remained on the floor of the central chamber, in which the 

 eggs or the young had evidently been lodged. I have on three occasions found the eggs 

 beneath the membrane in the angles of the arms, and, in a more advanced stage, congre- 

 gated in the central tent, but never under circumstances such that I could keep and 

 examine them ; exposed or loosely covered eggs or embryos, or any soft and pulpy organs 

 or appendages are always in a half disintegrated state when they are brought up from such 

 great depths, if they are not entirely washed away." 



2. Hymenaster formosus, Sladen (PL LXXXI. figs. 3 and 4; PI. LXXXIII. figs. 4-6). 



Hymenaster formosus, Sladen, 1882, Journ. Linn. Soc. Lond. (Zool.), vol. xvi. p. 213. 

 Marginal contour subpentagonal, interbrachial arcs very slightly indented, the minor 

 radius beiug in the proportion of 73 - 6 per cent. R=19 mm.; ?-=14 mm. General 

 form depressed, abactinal area rising slightly conoid in the centre. Radial areas not 

 specially defined although to a certain extent indicated, the paxilke-spinelets being con- 

 fined to the rays and not encroaching on the median interradial portion of the membrane. 

 Marginal fringe very narrow, faintly crenulated, tips of spines rounded and thickened. 



1 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 75; Voy. of Challenger, vol. ii. p. 239. 

 (zool. chall. exp. — part li. — 1888.) 63 



