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Show 88 SIR C. ELIOT ON NUOIBRANCHS [May 17, smaller numbers, being rare or completely absent from the shore of the Bay at other times. Most of the animals were of a bright dark yellow with the black liver showing more or less conspicuously through the transparent integuments, but the colour ranges in exceptional cases from deep orange to almost colourless transparency. Many specimens were infested with small light yellow copepoda found adhering to the body, especially on and near the gills. The alcoholic specimens are of a more or less yellowish white. The largest is 29 millimetres long, 12 high, and 8 broad, but, as a rule, the back is proportionately broader. The whole body is smooth and very soft. In most specimens the dorsal area, is bounded by a distinct lateral ridge. It is not visible behind the branchiae, but extends from them to the front of the head, where, however, it is not continuous but divided by a deep notch in the middle. In several specimens this rirlge is only clear in places and in a few it is absent altogether. The rhinophores bear about ten perfolia-tions and are set in such shallow pits that they can hardly be called retractile. They are exposed in the alcoholic specimens. The edges of the pits are smooth. The gill consists of from 20 to 34 leaflets *, set in a horseshoe or circle open behind, and placed rather far back. The leaflets are flat and compressed and decrease in size posteriorly. The largest bear on each side about ten lamellae, the smallest two or three. The whole appearance of the branchial apparatus is quite unlike Avhat is usual in the circum-anal plumes of nudibranchs and recalls the prosobranch gill. The foot is a narrow groove, but has a thin expanded margin, including which the breadth is 6 mm. in large specimens. The anterior margin of the foot is grooved and united with the corners of the mouth, where it is joined by a second ridge, which runs above it and apparently represents the tentacles. The tail is bifid. The radula has a wide bare rhachis, and the formula varies from about 11 x 10 +2.0.2+ 10 to 15x14 + 2.0.2 + 14. The innermost tooth is irregular in shape, but consists of a basal portion from one end of which rises a more or less bent spine, while another spine is more or less completely developed at the other end. The second tooth is larger and is more distinctly bicuspid. The other teeth are unicuspid, awl-like, and hardly bent; and those nearer the rhachis are rather stout, but they become slender towards the end of the row. All the different forms of teeth are well represented in Bergh's plates. In the nervous system the ganglia are very distinct. The liver is large, black, and very soft. On its anterior1 portion, and less detached from it than usual in the genus (e. g., than in T, coccinea described above), are two yellowish hermaphrodite glands of a somewhat irregular shape. Indeed, though separable from the liver, they cannot be said to be separate from it. This may be possibly due to the fact that the specimens are in good condition, so that the membranes connecting the # The gills as represented in the Plate are not Sufficiently numerous. |