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Description V
Animal small, 3-5 mm length, 1.2-3 mm width. Colour yellowish-white. Head valve semicircular,
with seven large wrinkled radial ribs, that start from the edge of an apparently smooth mucronal area.
The interstices are quincunxially granulated.
Intermediate valves (Figs 4-7) moderately elevated, subcarinated, with the posterior margin nearly
straight and apex slightly prominent. One highly elevated radial rib on either side, starts from the apex,
covered by scaly tubercles. The central area is sculptured by quincunxially disposed tubercles. Posterior
valve with the antemucronal area sculptured by large scaly tubercles. One wrinkled radial rib on either
side a little behind the antemucronal-postmucronal boundary. Postmucronal area quincunxially granula-
ted, but with the quincunxes arranged along concentric lines.
The ventral side of the intermediate valves is perlaceous, has two deep lateral dimples near the
apical area, with a marked radial grove. The insertion plate to the perinotum is divided by one deep
cut on either side in two smooth teeth. Teeth formula 8/2/7. Apophysis not well preserved, small and
triangular.
Dorsal surface of the girdle (Figs 10-12) covered with imbricating, roughly rectangular, close scales
(65-85x35-50 mm), the major sides regularly curved. The scales are externally sculptured by 12-13
axial riblets with 4-5 spherules (8-10 mm) on the upper margin, the external ones sometimes fusing
with the riblets. Ventral surface (Fig. 13) covered with slender and more regularly rectangular scales
(54x13 mm), smooth, radially arranged.
Radula of a 3 mm long specimen (UR92-7#2 stn.), about 1.1 mm long with nearly 37-38 rows of
mature teeth. The central tooth is enlarged anteriorly with sharp blade. First laterals subquadrangolar
(the presence of a knobby protuberance on the outer side was not evident in all teeth, in the optical pre-
parate). The second lateral is unicuspid, with a slender and narrow tip. The outer marginals are
markedly slender and elongated.

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