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Show 1904.] FROM EAST AFRICA AND ZANZIBAR. 385 teeth in them varies greatly and apparently increases with the size (that is probably the age) of the animals. As regards shape, the teeth present several types :- (1) They are simply bifid in cmrulea, semperi, nigrostriata, marenzelleri, crossei, thalassopora, camcena, lapinigensis. In these species the innermost tooth bears a single accessory denticle on the inner side and hence appears trifid. (2) They are bifid with accessory denticles below the bifurcation in gracilis, messinensis, sycilla, hilaris, bennetti, calif omens-is, and <zgas$izi. In runcinata the accessory denticles are very small and inconspicuous. (3) In scurra the apex of the tooth is three or five times cleft, and a somewhat similar arrangement, by which the denticles are all on the upper part of the tooth, appears to occur in pustulans, gloriosa, and rudolphi. (4) The commonest form of tooth is hamate, with several (6-10) denticles on the outer side. These are generally fine and minute, but in some forms (e. g., porcata, rosans, mariana, eliza-bethina, paupera, tryoni, and godeffroyctna) are large and strong. In this class of radula the innermost teeth have generally several denticles on each side, but sometimes (e. g., mbrchii and gonctto-phora) only one on the inside. Of the species described below, the first four are closely related, and form a group to which I a m almost disposed to accord generic rank. I have not done so out of deference to the high authority of Prof. Bergh, as one of the animals appears to be identical with the Goniobranchus reticularis of Pease, examined by him and referred to Chromodoris. All four forms agree in being oval and flat in shape, with a very ample mantle-margin. The consistency is very soft, and the dorsal pattern composed of spots, not stripes. The innermost teeth of the radula bear a few denticles on both sides; the rest 6-10 denticles on the outer side only. The branchiae are numerous, and the sides of the mouth are connected with the upper lamina of the grooved foot. This latter peculiarity was noted in the living as well as in the alcoholic specimens; but I a m not sure that it is of much morphological significance, for in a very soft animal with ample flaccid integuments such folds may easily be formed at the coiners of the mouth without constituting distinct structures. Nos. 12-15, described as hilaris, lineata, lineata var., and Imagnifica, are very likely all varieties of one striped species, with bifid teeth bearing accessory denticles, and about 10 branchiae, but a larger number of living animals must be examined before this identity can be established. All m y species which are not new have been previously found in the Indo-Pacific, which appears to be the head-quarters of the <*enus, though not enough is known of the Xudibranchs of the tropical Atlantic to make any comparison as to numbers of species. About half a dozen forms are reported from the "West Indies and the Gulf of Mexico. The genus is mainly tropical, and in |
