250 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Ophialcxa comes the nearest to the present species; but even from that genus it differs in the covering 
of the disk. For the present, however, it may remain in that group, characterized especially by the 
upper-arm plates being broadly in contact, the rows of arm-spines not approximating dorsally, mouth 
parts as in typical Ophiacantha. This Porto Rican species is nearest to 0. rufescens Koehl., which was 
collected in 470 fathoms off the Azores. It differs from that form in the number of arm-spines and in 
the covering of the disk and radial shields. The name glabra is suggested by the very smooth disk, 
the scales of which are very indistinct. 
44. Ophiopristis hirsuta (Lyman). 
This species occurs throughout the West Indies in water from 80 to 1,000 fathoms deep. It is 
light chocolate brown above, nearly white beneath, and reaches a diameter of 11 mm. One specimen 
from station 6070. 
45. Ophioplinthaca spinissima, nov. sp. (PI. 15, tigs. 9-12.) 
Arms 5, stout and very spiny. Disk almost circular, slightly indented in the interbrachial spaces, 
7 mm. in diameter. Arms about 30 mm. long; . \ R = 4i d. Arm 1J mm. wide at base. Disk covered 
by the radial shields and coarse scales; near the center it is depressed and carries numerous thorny 
stumps; these also occur elsewhere on the disk, in the interbrachial spaces below and at the distal 
ends of the radial shields. The latter are very large, about twice as long as wide, and are not simply 
in contact, but one actually overlaps the other. Upper-arm plates are very widely separated, broadly 
triangular in outline, slightly curved distally, and 2 or 3 times as wide as long. Arm-spines 9 (figs. 11 
and 12), slender, somewhat glassy, very thorny, the fourth longest and about equal to 2 joints; the 
rows approximate closely dorsally. First under-arm plate almost pentagonal, the point inward; 
farther out they become hexagonal, the distal side very short, and concave both distally and proxi- 
mally. Tentacle scale 1, large; sometimes the first one or more are divided into 2. Oral shields 
wide, much broader than long, narrowest without, wide and rounded within, the madrepore plate 
much the largest. Adoral plates large, quite broad, four-sided. Tooth papilla 1. Oral papillae 5 to 7, 
in a nearly simple row, the most distal ones widest; there may be 1 or 2 narrow papillae placed distally 
above these wide ones. Oral tentacle scale conspicuous. Genital slits very prominent, 2 in each 
interbrachial space. Color very light brown, variegated on disk with darker. 
Two specimens of this species were taken at station 6067, in Mayaguez Harbor, on coral bottom, 
in 97 to 120 fathoms. One is badly broken and much smaller than the one described above. They 
clearly belong to genus Ophiomitra as defined by Lyman, and in some respects resemble the common 
West Indian species O. valida; but the arrangement of the oral papillae seems to indicate their 
relationship to Verrill’s genus Ophioplinthaca, though in some other respects they differ markedly 
from that genus. They differ from Ophiomitra sens. str. in the simple row of oral papillae and in the 
close dorsal approximation of the rows of arm-spines, while they differ from Ophioplinthaca in the 
absence of special marginal scales. Were it not for the very close approximation of the rows of arm- 
spines, they might be considered young individuals of O. valida; but considering all their characters, 
it seems better to regard them as a new species of Ophioplinthaca. The name given was suggested by 
the very spiny arms. 
46. Ophioscolex serratus, nov. sp. (PI. 14, figs. 14-17). 
Arms 5, flat, slender, and very tapering. Disk almost pentagonal, the sides somewhat concave, 
6 mm. in diameter. Arms about 39 mm. long, .\ R=6J r. Arms about- H mm. in width at base. 
Disk covered by a peculiar flaky skin, which extends out on the arms; the surface is roughened 
by little flakes of a chalky material, between which it appears to be finely granular. Radial shields 
small, widely separated, showing through this skin, somewhat triangular, the apex pointing outward. 
Upper-arm plates wanting, the side-arm plates showing through the skin and giving a superficial 
appearance of upper-arm plates. Arm-spines 3 (figs. 16, 17), flat, very acute, and sharply serrate, the 
upper one longest, about equal to a joint and lying fiat against the arm. Under-arm plates squarish, 
with truncated corners, slightly concave distally. Tentacle scales wanting. Oral shields twice as wide 
as long, the outer side almost straight, the inner widely curved. Adoral plates narrow, about equally 
wide at the two ends, meeting within, but not without. Oral papillae 9, of which 1 is at the apex of 
the jaw; they are fiat, thin, and abruptly pointed. Teeth large, rounded, prominent. Genital slits 
prominent, 2 in each interbrachial space. Color of disk (speckled with the whitish flakes above) 
greenish-yellow; upper side of arms bright yellow; beneath very pale, almost white. 
