OPHIOCTEN. als? 
seen entire ; arm-spines three, the upper one rather long and stout, 
tapered, the others successively shorter and smaller; two tentacle- 
scales. Lower arm-plates rather small, transversely rhomboidal, 
with rounded lateral angles, the four sides concave, and the distal 
angle prominent; near the base of the arms the plates are in con- 
tact to a small extent, but farther out they are separated by the 
lateral plates. Upper arm-plates large, thickened, trapezoidal, 
toward the base of the arms broader than long, broadest distally, 
the proximal and distal edges nearly straight; farther out they 
become longer than broad, and much narrowed proximally. 
* Colour, in life, bright orange; in alcohol, white. Diameter of 
disk 18 mm.; its height 7 mm.; length of arms (minus tips) from 
centre of disk 45 mm. 
‘* Off Martha’s Vineyard, 192 to 310 fms. 
“Specimens of this singular species were sent to Mr. Lyman for 
examination last year. He considered it an undescribed species. 
It has no allies on our coast.” 
2. OPHIOCTEN. 
Ophiocten, Liith. Vid. Medd. 1854 (1855), p. 97; td. Dansk. Selsk. 
Skrift. v. (1859) p. 51; Lyman, Ill. Cat. M. C. Z. (1865) p. 53; 2d. 
Chall. Rep. Oph. (1882) p. 78. 
No tooth-papille ; teeth; mouth-papille not numerous. Disk 
not notched ; radial shields partly obscured by characteristic scaling 
of disk. Arm-spines solid, smooth, short, not stout. Bursal slits 
not very extensive. 
Allied to Ophiura, but more delicate. 
1. Ophiocten sericeum., (Plate XIII. figs. 1 & 2.) 
Ophiura sericea, Forbes, Sutherl. Voy. (1852) ii. p. cexv. 
Ophiocten kroyeri, Lith. Vid. Medd. 1854 (1855), -p. 102; id. Dansk. 
Selsk. Skrift. v. (1859) p. 52, pl. i. fig. 5; Lym. Ill. Cat. M. C. Z. 
(1865) p. 53; Ljungman, Gifv. Vet.-Akad. Forh. 1864 (1865), p.360; 
ad. op. cit. 1866 (1867), p. 307 ; Marenz. Denk, Ak. Wien, xxxv. 
(1878) p. 382. 
Ophiocten sericeum, Lym. Bull. M. C. Z. v. (1879) p. 102; Dune. & 
Slad. Greenl. Ech. (1881) p. 65, pl. iv. figs. 8-10 & 14; Lym. Chall. 
oe ee (1882) p. 79; Hoyle, Proc, Roy. Soc. Ed. xii. (1885) 
p. 720. 
A small and delicate species. 
The disk flattened, with a sharp edge, and covered for the most 
part with a scaling which renders indistinct the underlying plates, 
but a central circular plate with larger primary plates around 
it may be made out. Three to five distinct, proportionately well- 
developed mouth-papille; rather large, irregularly oval, mouth- 
shields ; elongated side mouth-plates. Arms flat, rather long; a 
comb on either side of the base of about seven. short spines, and a 
I 
