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Show 252 SIR CHARLES ELIOT ON NUDI13 RANCH S [Mar. 17, ends in two ridges near rhinophores, similarly edged ; front edge of velum similarly edged. Back grey, mottled with a darker shade, the top of the numerous longitudinal ridges being sprinkled with clear black spots. Underside white. Gills also white. Rhinophores longitudinally lamellated, grey in colour, and can be contracted or retracted, though the pockets do not seem very definite 01* complete." The somewhat bent alcoholic specimen measures 3 centim. from head to tail, but would be at least 5 longer if it were straightened out. The breadth of the back is l -5 centim., of the foot '6. The foot is long and narrow, pointed behind and truncate in front, the corners not projecting. No caruncle or nuchal papillae are visible, but it is somewhat difficult to reconcile the head-parts of the preserved specimen with the description quoted aboAe. According to a rough drawing made from the living animal, it would seem that the mantle-edge passes between the rhinophores and forms a sort of velum in front of them; but in the preserved specimen it appears to lie behind them as in an ordinary Pleurophyllidia, and not to pass through them at all. The salient character of the genus is that there are 110 branchiae and 110 trace of a branchial cleft. Lateral lamellae are, however, present. They are situated exclusively on the under edge of the mantle, and not 011 the sides of the body. They extend from the head to the tail, and are about 30 in number on each side. They are irregular in size and shape. Some terminate before they reach the mantle-edge, and some run from the mantle-edge only halfway to the body. The genital papilla is 4 millim. and the vent 1*2 centim. from the anterior end of the body. Cnidophores are distinctly visible round the edge of the mantle. The mouth is ventral, and forms a large transverse slit, with slight indications of a T-sliape. The jaws are yellow, narrow, and united so as to form a shape like a boat. They bear no denticles, but there are a few irregular coarse indentations of the edge, due apparently to its being jagged by use. The radula consists of about 30 rows, the formula for each of which is about 50-f 1 + 50. The central tooth consists of a squarish basal plate with a long cusp, which bears about 10 denticles on each of its sides. The first lateral is larger than the others and resembles the central tooth, except that the denticles are only on the internal side. The second and third laterals are also denticulate; the rest appear to be simply hamate. This form appears to be intermediate between Pleuroleura, which has neither branchial clefts nor side lamella?, and Pleurophyllidia, which has both. I have indicated its affinities by the 11am e Pleurophyllidiella. B uEOLid ia m ajor, n. sp. (Bergh, in Semper's Reisen im Arch. Philipp., Malac. Untersucli. vol. iii. pp. 778-780, 1880.) |
