REPORT ON THE ASTEROIDEA. 473 
2. Pteraster affinis, Smith. 
Pteraster affinis, E. A: Smith, 1876, Ann. and Mag. Nat. Hist., ser. 4, vol. xvii. p. 108; Phil. Trans., 
Zool. Kerguelen Island, 1879, vol. clxviii. p. 275, pl. xvi. fig. 5. 
Locality.—Station 149p. Royal Sound, Kerguelen Island. January 20, 1874. Lat. 
49° 28’ 0” S., long. 70° 13’ 0” W. Depth 28 fathoms. Volcanic mud. Surface tem- 
perature 41°:0 Fahr. 
3. Pteraster rugatus, Sladen (Pl. LXXIV. figs. 3 and 4; Pl. LXXVII. figs. 3 and 4), 
Pteraster rugatus, Sladen, 1882, Journ. Linn. Soc. Lond. (Zool.), vol. xvi. p. 192. 
Marginal contour subpentagonal, interbrachial arcs scarcely indented, the minor radius 
being in the proportion of 68°4 per cent. R=9°5 mm.; r=6'5 mm. Interradial margin 
rounded, extremities of the rays slightly upturned, exposing the end of the furrow. Abac- 
tinal profile rounded, not high, tapering but little towards the extremities of the rays. 
Actinal surface flat or slightly convex. Lateral fringe very slightly produced beyond 
the margin of the test. 
The supradorsal membrane is subcorrugated and is not reticulated. The paxille- 
spinelets are fine, about five or six in number, and their tips are slightly protuberant, pro- 
ducing a slight papillate appearance on the abactinal surface ; no regularity of arrangement 
is perceptible. The membrane is indurated with minute spicules averaging 0°03-0°04 mm. 
in length, which are small, irregular, and angularly-branching bodies, subdendriform in 
appearance and fairly well spaced. The spiracula are rather large, not numerous, and are 
irregularly placed. 
The ambulacral furrows are narrow, uniform in breadth till near the extremity, and 
not petaloid. The ambulacral tube-feet are disposed in regular simple pairs. The arma- 
ture of the adambulacral plates consists of short and rather robust spinelets, three or four 
in each comb, but three only on the outer part of the ray. The innermost spine is nearly 
as long as the others, or, if a small inner one be present, it may be more or less aborted 
and invisible without dissection. The web is remarkably thick and fleshy, subsaccular 
over the spinelets, and passes off from the outermost spine with a long gentle sweep far 
out upon the lateral fringe. 
The mouth-plates each bear on their margin about three rather short, robust mouth- 
spines webbed together. There is one secondary or superficial mouth-spine on the actinal 
surface of each plate, perpendicular to the plane, longer than any of the other spines, 
exceedingly thick, triangular, translucent, sharply. pointed, and covered with a thick fleshy 
investment. 
The aperture-papille are large, prominent, and subtriangular. The actino-lateral 
spines, which are directed ,horizontally, are comparatively long, specially in the inter- 
radial area. The web is rather thick and fibrous. 
Colour in alcohol, greyish white. 
(ZOOL, CHALL. EXP,—PART LL.—1888,) 60 
