Disc, circular, flattened, its aboral surface covered by scales of various sizes, amongst which the primaries and the radial shields are prominent. The scales partly imbricate and partly interlock. The six primary plates—namely, the dorso-central and the five radials—are large, contiguous, extend from the centre to halfway to the periphery, and shape the pattern of the English heraldic tudor rose. Adjoining the radial primaries, and interradial in position, occur five irregularly pentagonal plates, one to each iuterradius, and evidently also belonging to the primary system, Adjoining the radial distal border of each primary radial plate there are three small scales arranged as a trefoil, the middle leaflet of which is inserted between the proximal ends of the two adjoining radial shields. The radial page 17 shields are polygonal, about as broad as long, mutually contiguous. The rest of the aboral surface of the disc is covered by rather large plates, smaller, however, than those already mentioned, and disposed in a less regular manner. The adoral surface of the disc is clothed in coarse, imbricating scales. Genital clefts extend to the Second arm-segment. Oral shields subtriangular, with a proximal acute angle and a distal convex base. Adoral plates subtriangular, larger than the oral shields, meeting broadly (or even overlapping) within. Three pairs of oral papillae, one pair infradental, one pair carried on the oral plates, the outermost borne on the adoral plates. All the oral papillae are large, leaf-shaped, and the two inner pairs have pointed tips.