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Show 1904.] FROM EAST AFRICA AND ZANZIBAR. 95 and 7 broad in tbe widest part, but one which was dissected was about twice as large. The colour has become pale green, with a white reticulation on the sides and white stripes on the back. The skin is quite smooth, and there are no tubercles whatever. There are nine or ten pairs of branchiae, of which the last three are quite small. The rhinophores have long raised sheaths with simple edges; the club is surrounded by six bipinnate plumes. The velum bears at each end a small grooved tentacle of the usual shape and six processes. The two in the middle are simple and smaller; the other four are larger and branched. The jaws are white and membranous in the smaller and probably immature specimen, yellow and corneous in the larger one. In both there are from 20-30 very large blunt denticles, and also undulations near the edge of the jaw, which in the larger specimen sometimes develop into denticles, so that in about half the length there are two rows of denticles and here and there three. The radula consists in one specimen of 47 and in the other of 45 rows, with a formula of about 80 + 1.1.1 +80, which rises to as much as 85 marginals in one and 100 in the other for a few rows. The central tooth is broad and tricuspid ; the median cusp is taller than the others, but not very pointed; all the cusps are rather irregular in shape, and have indentations here and there on the edges. The first lateral tooth is large, blunt, and very different from the rest in appearance. The others are hamate. The stomach has a girdle of about 150 horny, yellow, triangular plates of different sizes. I do not think that this species can be identified with any of the forms the descriptions of which I have seen *. The coloration somewhat resembles Tritonia rubra Leuckart and Tr. hawaiensis Pease, but the other details do not coincide. The species differs from the others hitherto found in East Africa in being quite smooth and having no tubercles. M a r io n ia arborescens B . [Bergh, in Semper's Reisen, xvii. pp. 890-894.] One specimen from near Wasin. The notes on the living animal suggest that it is the same species as M. ramosa, and say that it differs chiefly in that the branchiae, rhinophores, and processes of the velum are much smaller. The colour appears to have been the same as in that species (i. e. cocoa and green), and it is noted that there was a greenish tinge in the branchiae. The back was warty. The alcoholic specimen does not look much like M. ramosa. It is rather bent, but the length appears to be about 21-5 millimetres, the breadth 11*5, and the height 9. The back and sides are covered with flat low tubercles and the epidermis comes off in flakes. The dorsal margin is unusually prominent and projects 3'2 mm. It * In this group as in others I have not access to the descriptions of a few forms by the older writers, e. g. Tr. palmeri. |
