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Show 1904.] FROM EAST AFRICA AND ZANZIBAlt. 97 there, looks as if there were five cusps, but the median cusp is in this specimen thinner and more pointed than in the plates. The liver is large and yellowish. Embedded in the front part of it is the stomach, consisting internally of a large, soft, laminated portion, and a ring of about 120 yellowish, fairly stiff, horny plates. They are not all of the same size, the largest being 2 millimetres long and 1 high, and the smallest about half as large. This species will perhaps prove to be only a variety of M. arborescens, from which it is distinguished chiefly by its long ribbon-like branchiae, which give it a remarkable appearance. The jaws also present some differences. M a r io n ia a l b o -tu b e r c u l a t a , sp. n. One specimen from the neighbourhood of Wasin, East Africa. Dredged. According to the notes on the living animal the sides were opaque white, with a reticulate pattern of red-brown. At the centre of each mesh was a small white projection. The back, which was dark brown at the sides and greyish in the centre, bore a similar arrangement of reticulations and projecting spots. The sheaths of the rhinophores were tall, and the wavy edges were turned over outwards. The branchiae were much subdivided, and very large when fully extended. The main stems were of a light greenish grey, and the finer branches of a dark yellowish brown. The velum was plate-like, with five processes on each side, three of which were branched. The alcoholic specimen is 45 millimetres long, 15 high, and 13 broad. It does not taper to a point behind. The colour is dirty yellow with profuse white markings. The stems of the branchiae are spotted and striped with white. There are nine pairs of branchiae of which the fourth is the largest, but the left-hand plume of this pair is much larger than the other. The middle and left-hand side of the velum are injured. There remain on the right-hand side, starting from the inside, (a) a bifid process, with three branches on each bifurcation, (b) a simply quadrifid process, (c) a simply bifid process, (d) a quite simple process, (e) a tentacle grooved below. Taking into consideration the notes on the living animal, it app3ars that there was a similar arrangement on the left side and that the middle of the velum was smooth. There is a small oval papilla below the fourth branchia, close to the dorsal margin. The genital papilla is lower down between the second and third branchiae. The jaws are yellow, horny, and large, being 9 millimetres long and 4 wide. They bear a single row of strong denticles, 10 of which are very much larger than the rest. Under five of the largest are indications of a second row. The radula is yellow, and consists of forty rows with a maximum formula of 95 + 1.1.1 + 95. The central tooth is fairly broad and bears three cusps, of which that in the middle is pointed and those at the sides blunt. The P roc. Z ool. Soc.- 1904, Y ol. II. No. Y I I . 7 |