can se ed 
REPORT ON THE ASTEROIDEA. 367 
Genus Rhegaster, Sladen. 
Rhegaster, Sladen, Trans. Roy. Soc. Edin. 1883, vol. xxxii. p. 155. 
Marginal contour subpentagonal; rays slightly produced. Abactinal surface more or 
less convex, actinal flat. The whole body covered with membrane beset with crowded 
spinelets. 
Abactinal skeleton composed of irregular plates, crowded and subimbricated in places, 
which leave small irregularly disposed meshes. The whole skeleton hidden in a thick 
membrane, and furnished with a compact covering of small, uniform, crowded spinelets. 
Papulze small, numerous, isolated, irregularly distributed over the whole area. 
Infero-marginal plates large, forming the margin of the test. Supero-marginal plates, 
superficially invisible, concealed in the abactinal membrane. 
Actinal interradial areas with large subrecular plates, hidden by a superficial mem- 
brane, with small crowded spinelets. 
Adambulacral plates broader than long. Adambulacral armature consisting of short 
spines thickly invested with membrane, which form a regular furrow series, and several 
subregular longitudinal rows externally. Tube-feet in simple pairs, with a small sucker 
disk. 
Madreporiform body small, midway between the margin and the apex. 
No pedicellarize. 
Remarks.—This genus was established for the reception of a starfish dredged during the 
“Triton” cruise ; and I have also referred to it the form which was named by Stuxberg * 
Solaster tumidus, but which was afterwards ranked as an Asterina by Danielssen and 
Koren.” 
Through the kindness of Professor Lovén, I have had the privilege of examining Dr 
Stuxberg’s type specimens in Stockholm, and I entirely agree with Drs Danielssen and 
Koren in regarding the original reference of the form to Solaster as altogether untenable. 
Chorology of the Genus Rhegaster, 
a, Geographical distribution :— 
ATLANTIC: Two species between the parallels of 60° and 85° N, 
Rhegaster tumidus off Nova Zembla, Spitzbergen, the coasts of 
Norway and Siberia. A variety (twberculata) has been described by 
Danielssen and Koren which occurs between Norway and Spitzbergen. 
Rhegaster murrayi in the Faerée Channel, 
1 Ofversigt K. Svensk. Vet.-Akad. Forhandl., Arg. 35, 1878 (1879), No. 3, p. 31, pl. vi. 
2 Nyt Mag. f. Naturvidensk., Bd. xxvi. Hft. 2, p. 182, pls. i. & ii. figs. 6-10. 
