64 PROCEEDINGS OF THE ACADEMY OF [Feb., 



Verrill), Ophiomitra dicycla H. L. Clark, Ophiothamnus Icevis Lutken 

 and Mortensen, and Ophiothamnus stultus Koehler are not genuine 

 Ophiothamnus, but belong to a distinct type, which awaits a name, 

 being more or less related to Ophiomytis and Ophioplinthaca. 

 Ophiolebes tuberosus sp. nov. 



Diameter of disk 10 mm. Length of arms 38 mm. Width of 

 arms at base 1.5 mm. Disk five-lobed, with strongly concave 

 interbrachial borders, deeply hollowed at the central region, covered 

 by a thick, cereous skin, which contains well-spaced, thick, rounded 

 scales of various sizes; beset with several short, conical, stout, 

 obtuse tubercles, which are larger and more numerous on the radial 

 shields. Radial shields also covered by the skin, long, narrow, 

 bar-like, strongly raised, about two-thirds as long as the disk radius. 

 Ventral interbrachial areas covered by a skin similar to that of the 

 dorsal side, the scales and tubercles being, however, smaller. Genital 

 slits large, long, but not reaching disk margin. Oral shields small,, 

 thick, rhomboidal, wider than long, with wide, rounded outer angle 

 and convex surface. Adoral shields large, quadrangular, with 

 perfectly rounded outer angles and strongly convex surface, wider 

 without than within, meeting each other. Between each pair of 

 oral plates occurs a more or less distinct buccal pore. Three, or 

 sometimes four, oral papillsB on either side, conical and blunt; inner 

 ones smaller; outermost papilla, very large and stout. Oral papillae 

 project laterally beyond radial axis, and those on opposite sides of 

 each oral slit are placed alternately. Teeth conical, stout, obtuse. 



Arms slender, covered by a thin, cereous skin. Dorsal arm plates 

 two to each joint; proximal plate small, quadrangular, wider than 

 long, with a convex surface; on distal part of arm it becomes longer 

 than wide; distal plate large, fan-shaped, much wider than long^ 

 and with a convex surface. Dorsal side of arm bases covered by 

 continuation of disk covering, so that it bears thick, rounded scales 

 of various sizes in place of dorsal arm plates. Lateral arm plates 

 somewhat flaring, meeting below for a short distance. First ventral 

 arm plate comparatively large, hexagonal, with concave inner side 

 and convex surface, widest at the lateral angles, as long as, or slightly 

 longer than, wide, in contact with the next plate; the latter is the 

 largest of all, pentagonal, widest at lateral angles, as long as, or 

 slightly longer than, wide, with convex surface and a conspicuous 

 notch in distal margin; following plates separated from each other^ 

 rhomboidal, with a conspicuous notch in distal margin, with strongly 

 convex surface; distally they become smaller, oval or rounded, and 



