BATHYBIASTER. 69 
superomarginals have no ridge and are not channelled ; the spines 
are not enclosed in sheaths, and those on the sides of the ambulacral 
groove are subequal, numerous, and in a straight row. 
1. Psilaster andromeda. 
Astropecten andromeda, M. Tr. Syst. Ast. (1842) p. 129; Did. &§ 
Kor. Vet.-Akad. Hdlg. 1844 (1846), p. 250, pl. vil. figs. 18 & 19; 
Sars, Norg. Ech. (1861) p. 30: Duj. § Hup. Echin. (1862) p. 420; 
Mob. § Biitschli, JB. Comm. Kiel, ii. & iii. (1875) p. 148; Kor. 
§ Dan. Nyt Mag. xxiii. (1877) p. 65; wd. Norske Nordhavs 
Asteroidea, (1884) p. 81, pl. xiv. fig. 16. 
Astropecten christii, Diib. § Kor. Gifu. Vet-Akad. Forh, 1844 
(1845), p. 113. 
Psilaster andromeda, Sladen, Chall. Rep, Ast. (1889) p. 224. 
R=32r to 4:2 r. 
Arms well marked off from disk, with rather deep sides, tapering 
regularly but not rapidly to a somewhat sharp point. Ambulacra 
wide, bordered by a single row of rather delicate spines, of which 
there are about eight on each plate; beyond these are three rows of 
shorter and finer spines, two or three in each row. The infero- 
marginals are large, much wider than long, bear a few spines and 
a number of scale-like tubercles, in some cases covered by membrane. 
The superomarginals, of which there are 30 to 40 on the side of 
every arm, correspond in number to the inferomarginals ; they are 
characterized by the presence on them of rather large scales, but on 
them, as on the lower plates, the central part is, in dry specimens, 
bare. The plates of the dorsal surface are small, with delicate 
paxillar spines; the madreporite, which is not conspicuous, is rather 
nearer the margin than the centre of the disk. 
Breadth of arm 
R. r. at base. Height of do. 
69 16°5 16 10:5 
64 175 17 10 
55 16 14 9 
40 12°5 11°5 7 
Distribution. European coast, from Bay of Biscay to Kola Penin- 
sula. 40-690 fms. 
a. 59° 37'N., 7° 19’ W., 530 fms. Voy. ‘ Knight Errant’ (St. 7). 
b. 59° 40' N., 7° 21' W., 516 fms. Voy. ‘ Knight Errant’ (St. 10). 
ce, d. 59° 29' N., 7° 13' W., 555 fms. Voy. ‘ Knight Errant’ (St. 11). 
e. 50° 29' 26” N., 11° 4’ W., 400 fms. G. C. Bourne, Esq. 
4. BATHYBIASTER. 
Bathybiaster, Dan. § Kor. Nyt Mag. xxvii. (1883) p. 285; tid. Norske 
Nordhavs Aster. (1884) p. 94; Slad. Chall. Ast. (1889) p. 175; 
Bell, P. Z. S. 1891, p. 230. 
Astropecten (pars), Dan. § Kor. Nyt Mag. xxiii. 3. (1877) p. 62. 
Flattened, with very wide ambulacra, at the sides of which lie 
