MUSEUM OF COMPARATIVE ZOOLOGY, 145 
Seven or eight slender, feebly thorny arm-spines; the upper one longest 
(3 mm.), the three lowest about equal. Tentacle-scales long, large, and pointed. 
Color in alcohol, gray. 
Btation 3, 1530 fathoms, 1 specimen. 
The only specimen was a disk with the bases of the arms and a few arm- 
spines. The characters were, however, distinct. 
Ophiacantha cornuta sp. nov. 
Plate X. Fig. 266. 
Special Marks. — Disk-scales distinct and rather large, closely beset with 
small stumps, having a slender trunk bearing a crown of six or eight minute 
thorns, Lowest arm-spine thickened and curved. 
Description of an Individual (Station 171).— Diameter of disk 5.5mm. Width 
of arm without spines 2mm. Seven mouth-papille to each angle, of which 
the three innermost are long, cylindrical, and pointed ; the odd one at angle of 
jaw being largest. Mouth-shields much wider than long, with a curve without 
and an obtuse angle within ; length to breadth .6 : 1.2. Side mouth-shields 
wide and stout, broadly joined within. Under arm-plates much wider than 
long, slightly curved without, having a little peak within, and the very short 
lateral sides re-enteringly curved ; length to breadth .6 : 1.2. Upper arm- 
plates small, much wider than long, almost of a transverse diamond-shape, 
and lower than the ridge of the side arm-plates, which are large, meeting 
broadly above and below, and have an unusually narrow projecting spine-ridge 
continuous over the top of the arm. Disk, including radial shields, covered 
by distinct imbricated scales, two or three in the length of a mu, closely bese“ 
and partly obseured by little stumps consisting of a slender trunk bearing a 
crown of six or eight minute thorns. Eight translucent arm-spinos, all sharp 
and strongly thorny, except the lowest, which.is thickened, curved, and slightly 
rough. Towards end of arm this spine is more curved and proportionately 
larger, and stands below three very slender arm-spines (Pl. X. Fig. 266). 
Tentacle-scale flat, stout, pointed. Color in alcohol, white, 
This specimen was plainly not fully grown, and. was imperfect by loss of 
some arm-spines, ctc., but the adult does not probably differ much, while the 
hooked lowest arm-spine and character of disk mark it well as a species. A 
young individual (Fiji Islands), with a disk of 3 mm. and arms 14 mm. long, 
presented no variations beyond those of age, except that the lowest arm-spine 
was rather less curved ; there were four spines besides this, the uppermost 
being sometimes jas long as 1.7 mm. 
Station 170, 520 fathoms. Station 171, 600 fathoms, Fiji Islands, 520 fathoms, 
