MUSEUM OF COMPARATIVE ZOOLOGY, 100 
side thorns, It is to be noticed that the size and shape of the tentacle-scale, 
when specimens of the same size are compared, give a pretty constant character 
in Ophiacantha and. Ophiomitra. 
Station 87, 1675 fathoms, 2 specimens. 
Ophiomitra dipsacos sp. nov. 
Plate VIII. Figs. 213-215. 
Special Marks. — Üpper arm-spines long and slender, marginal disk-plates 
large and swollen ; central disk-scales fine, and bearing minute thorny stumps ; 
arm wide. 
Description of an Individual (Station 24). — Diameter of disk 10 mm. Width 
of arm without spines 3.4 mm. Mouth-papille nine to eleven to each angle, 
whereof the innermost odd one is flat spearhead-shaped ; and the two outer 
ones on each side are ill-defined, being sometimes small papille, or again 
forming a sort of curled sheath to the mouth-tentacle ; the other papilla are 
pointed and flattened. Mouth-shields as long as broad, small, having an 
obtuse angle within, and a truncated angle or a deep curve without; 
outer edge often a little curled; length to breadth 2:2. Side mouth- 
shields wide, with outer side strongly curved. Under arm-plates, near 
base of arm, large, much. wider than long, with an outer edge gently curved 
and slightly thickened, and reaching nearly across the arm ; lateral sides 
re-enteringly curved, with a peak within, where each plate is separated from 
its neighbor by the side arm-plates, Upper arm-plates slightly swollen, 
bounded without by a gentle curve, and within by a deep curve or truncated 
angle ; they are separated by side arm-plates, which are prominent, and meet 
freely above and below. Disk thick and puffed, rising well above the arms, 
with a constriction and furrow in each interbrachial space, The area between 
this constriction and the radial shields, on either side, is occupied by four trans- 
verse plates running diagonally inward, and outside these is a similar larger 
plate forming the margin of the disk. Central disk covered with fine over- 
lapping scales, eight or ten on a line between central point and inner angle of 
radial shield ; they are sparsely beset with minute stumps bearing a crown of 
thorns. On the disk margin, over each arm, a few small grains or stumps. 
Radial shields of a wide pear-seed shape, with an angle inward, nearly or quite 
joined without; separated within by a broad wedge of scales; length to 
breadth 2.8: 1,7. Near base of arm six strongly thorny, glassy, cylindrical 
arm-spines, whereof the two upper ones are very long, slender, and tapering, 
and the lowest is thick and blunt; lengths to that of an arm-joint 5, 7, 3.5, 2.5, 
2,1.8: 1.8, Two large pointed tentacle-scales on first pore ; one on each of 
those beyond ; toward middle of arm, the scales are more elongated and pointed, 
and have one or two microscopic thorns, Color in alcohol, very pale brown. 
Station 24, 390 fathoms, 1 specimen, 
