154 BULLETIN OF THE 



Sir "WyAuUe Thomson loc. cit. records his specimen from Station 87. Tliis 

 was never sent me ; the only Ophiomitra from Station 87 being the allied 

 species 0. carduus, which does not agree with his figm-e and description of 

 0. chelys. The statement (p. 65) that the arm is only three and a half times the 

 diameter of the disk is plainly a misprint. 



Ophiomitra carduus sp. nov. 



Plate IX. Figs. 336 - 338. 



Special Marks. — Outer edges of under arm-plates swollen. Tentacle-scales 

 strongly thorny. Under arm-spine straight. 



Description of an Individual (Station 87). — Diameter of disk" 10 mm. Width 

 of arm without spines 2.8 mm. Mouth-papillse nine to eleven to each angle, 

 of which the inner central one has a flat spearhead-shape ; the others irregu- 

 larly conical with blunt points ; several of them much larger, and resembling 

 the innei'most one ; others, especially the outermost, small, crowded, and ill- 

 defined. Mouth-shields small, broader than long, with an obtuse angle within 

 and a truncated angle or a broken curve without, outer edge somewhat in- 

 dented ; length to breadth 1.7 : 2.2. Side mouth-shields very broad and 

 curved on their outer edge, almost crescent-like. Under arm-plates near base 

 of arm large, much wider than long, with a small swelling at their outer edge, 

 which is gently curved and reaches nearly across the arm ; lateral sides re- 

 enteringly curved, with a peak within, where each plate is widely separated from 

 its neighbor by the side arm-plates. Upper arm-plates somewhat swollen, 

 bounded without by a gentle curve, and within by an obtuse angle or a deep 

 curve. Side arm-plates stout and prominent, meeting broadly below, and, 

 beyond the third plate, above also. Disk moderately thick, rising somewhat" 

 above the arms, with a deep constriction in each interbrachial space. The area 

 between this constriction of the radial shields is occupied on either side by four 

 or five transverse plates running diagonally inward, whereof one or more are 

 often broken in two. Central disk somewhat sunken and covered with coarse, 

 irregular, overlapping scales, which, with the larger plates and edge of disk, 

 are closely beset with little cylinders bearing a crown of thorns. Radial 

 shields of an irregular pear-seed shape, with an angle inward, wavy, scarcely 

 sunken, very wide, separated by a broad wedge of scales forming a median 

 hump or ridge ; length to breadth 3.7 : 2. Near base of arm, six rather stout, 

 thorny, glassy, blunt cylindrical arm-spines, the lowest ones shortest and 

 stoutest, but not curved ; lengths to that of an arm-joint 3.3, 3.3, 2.1, 1.8, 1.8, 

 1.7 : 1.3. Beyond first pair of pores the tentacle-scales are cloven, or have a 

 long point, with one or more side thorns ; towards middle of arm these thorns 

 become stronger and the scale more pointed. Color in alcohol, dull straw. 



A smaller specimen, with a disk of 8 mm., had arms about 65 mm. long. 

 The disk-stumps were more thorny than in the larger one, and the tentacle- 

 Bcalus, beyond middle of arm, were short spines, with several sharp, slender 



