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Show 406 ON NUBIBRANCHS FROM EAST AFRICA AND ZANZIBAR. [Mar. 1, large posterior tubercle. The openings of the rhinophores have slightly raised but smooth edges; the rhinophores themselves are long, straight, and thin, and bear about 30 perfoliations. The tripinnate branchiae appear to be nine in number, but are so deeply cleft that it is hard to say how large a group should be taken as the unit. The foot is narrow and not very clearly marked off from the head ; it is distinctly but not deeply grooved in front. The internal anatomy is as described by Bergh. Both the labial armature and the radula are bright yellow. The former consists of small rods, straight or bent, but in all cases hooked at the end and not bifid. The teeth of the radula are somewhat irregular in shape, but no denticulations are discernible; the innermost teeth close over the rhachis. The oesophagus widens out into a distinct dilatation before entering the liver. EXPLANATION OF THE PLATES. PLATE XXIII. Fig. 1. Chromodoris reticulata (p. 386). Anterior end, showing relations and proportions of head, foot, and mantle, a, ridge connecting head and foot; b, groove in anterior edge of foot; m, mouth. 2. Diagram of the arrangement of the gills, the positions of which are shown by transverse sections of their bases : a, anus. 3. A single gill cut across, showing r., rachis ; h.v., blood-vessels; and^>., portions of three of the pinna; borne on the sides of the rhachis. 4. Portions of the radula. a, central teeth; b, the form of the majority of the teeth ; and c, those intermediate in shape and position between a and b. 5. The alimentary canal. The liver is cut away and the stomach laid open. b. Buccal mass. sal. Salivary gland of right side. st.c. Thin-walled anterior diverticulum of stomach. st.tn. Muscles in stomach-wall. g. Gills. I. Cut surface of liver. Id. Ducts of liver opening into stomach. 6. C. sykesi (p. 387). A living example. 7. C. cava, from life (p. 388). tn, edge of mantle; f, edge of foot. 8. Diagrams of the arrangement of the gills, a, from an example which had 16 gills; b, from one with only 12. PLATE XXIV. . 1. Chromodoris annulata (p. 389). Central teeth of radula. 2. Diagram showing positions of bases of gills : a, anal papilla. 3. A living example. The purple border of the mantle is continuous all round, but is in this case hidden in places by the folding down of the free mantle-edge. 4. C. elizabethina, var. africana (p. 392). 5. C. nigrostriata (p. 394), dorsal view. 6. Side view of the same. (The number of branchiae was in reality seven, not nine as here depicted.) 7. C. lineata (p. 396). Teeth of radula : a, from outer, and b, from central part. 8. C. flava (p. 399). Living specimen, a. Anterior corners of foot, which may or may not project beyond mantle-edge (cf. tig. 9). 9. Ventral vieir of the same showing narrow foot with its prolonged anterior corners and transverse groove, and proportions of head and mantle. |
