614 
THE VOYAGE OF H.M.S. CHALLENGER. 
is occupied with largely developed permanent primary plates, tlie regularly placed 
symmetrical interradials (basals), radials, and underbasals being especially prominent and 
conspicuous. The rays are covered with large, subhexagonal and slightly convex plates 
arranged in perfectly regular longitudinal lines, the plates diminishing regularly in size 
as they proceed outward, and those of the median line being the largest. The plates 
bear a few widely-spaced semicircular translucent granules, and a single large papula 
occurs in the interspace left at the angles of adjoining plates. Each adambulacral plate 
bears two short, thick, cylindrical spines, one directed towards the furrow and the other 
outward, which form two regular longitudinal series. External to the adambulacral 
plates is a complete longitudinal series of plates which bear two or rarely three spines 
placed side by side, and on the inner portion of the ray a few additional plates similarly 
armed form an incomplete pseudo-ventral series in large specimens. A few small 
pedicellarise (forcipiform) are present on the lateral regions of the ray, and also, but less 
frequently, on the abactinal area in the neighbourhood of the papulae. 
“ In the Southern Ocean the genus Hymenaster occurs in depths varying from 1375 to 
1950 fathoms, and Brisinga also shows a similar bathymetrical range. Both were dredged 
at three Stations, but were associated only at one, Station 146 (1375 fathoms). Pararch- 
aster, though likewise found at three Stations in depths varying from 1600 to 1900 fathoms, 
occurs in company with Brisinga only at Station 147 (1600 fathoms) ; and this genus is not 
found associated with the Pterasteridse in any area. The allied genus Pontaster occurs at 
Station 146 along with Hymenaster and Brisinga above mentioned. The genus Leptopty- 
chaster is associated with Brisinga at Station 156, south of the 60th parallel, at a depth of 
1975 fathoms, and is accompanied by an interesting new form, remarkable for the way in 
which it appears to unite the characters of Echinasteridse and Goniasteridse mimetically. 
Chitonaster is a small stellate Asterid, with convex and inflated disk and short rigid rays. 
The abactinal surface of disk and rays with short thick isolated and well-spaced rigid 
conical truncate spinelets, each appearing as if standing perpendicularly on a hexagonal 
plate, the whole surface at the base of the spines being covered with membrane. A double 
series of marginal plates are present, likewise hidden in membrane, the inferior the larger, 
and each plate with three spinelets similar to those above described, forming a line 
transverse to the axis of the ray ; the supero-marginal plates with one or two spinelets. 
The armature of the adambulacral plates consists of three isolated spines forming a line 
transverse to the furrow and similar to the other spines. Actinal interradial areas very 
small. No pedicellarise. 
“ The Porcellanasteridse are represented in the Southern Ocean only by a species of 
Hyphalaster , which occurs in company with Hymenaster at Station 157 at a depth of 
1950 fathoms. 
“ In the Eastern or Malay Archipelago only six genera of Starfishes occur at depths 
greater than 1000 fathoms. In the area north of the Equator are Brisinga and Pontaster, 
