608 
THE VOYAGE OF H.M.S. CHALLENGED. 
“ Twenty-six -genera of Starfishes have been found living in depths greater than 1000 
fathoms, and all but eight of these were discovered by the Challenger. 
“ In the abyssal depths beneath this limit in the Atlantic the Archasterkhe predominate; 
in the Pacific, on the other hand, the Pterasteridae and Porcellanasteridae are the most 
conspicuously represented ; whilst the Asterld fauna of the great Southern Ocean holds 
somewhat of an intermediate character, between the two. 
“ In the Atlantic the Pterasteridae are represented by the genus Hymenaster (fig. 202), 
which in the South Atlantic at Station 325 descends to a depth of 2650 fathoms. At the 
Fig, 202. —Hymenaster sacculatus. Sladen. Abactinal aspect. Slightly enlarged. 
same Station was dredged the genus Dytaster, an Archasterid type with a more or less 
inflated disk, and having very long attenuate rays, subearinate along their median dorsal 
line, and very slightly flexible. The marginal plates, which form a square vertical wall, are 
granulated, and each plate of either series bears one thin, thorn-like spine. Abactinal area 
covered with small rounded scale-like plates, bearing pseudo-paxil lse which form a closely- 
packed covering, in which no order of arrangement is discernible. Papulae distributed 
over the whole area. Actinal interradial areas well developed, with plates arranged in 
more or less definite columns. Armature of the adambulacral plates in longitudinal 
