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Show FROM EAST AFRICA AND ZANZIBAR. 105 from various points. The external characters are those of the genus. The mouth-parts on the whole resemble those of PI. striata as described by me (I. c.). The formula of the radula is 23x6 + 1.1.1 + 6. The rhachidian tooth has a long central cusp and about six denticles on each side. The first lateral is practically half the rhachidian tooth, having one tall cusp and about six denticulations parallel to it and rising from the base on the outside. The remaining teeth are simply hamate. The jaws are more membranous than in PI. striata, and bear six distinct rows of denticles. This form is closely allied to PI. striata, but differs strikingly in colour, that animal being black with yellow lines. Such variation in colour is not impossible within the limits of a species, but in this case it is accompanied by other differences:-(1) The shape is more elongate; (2) the radula is narrower; (3) the first lateral is differently shaped. These points seem sufficient to constitute provisional specific rank, though it is quite possible that the form may ultimately prove a mere variety of PI. striata. E X P L AN A T IO N OF TH E PLATES. P l a t e I I I . Figs. 1 a-1 g. Notodoris minor, p. 84. 1 a. Lateral view of living animal. 1 b. Dorsal view of living animal. 1 c. Hinder part of body with the valves raised and spread. 1 d. Gills with the valves removed. 1 e. Ventral view of anterior part of body. 1 f . Gians penis. 1 g. Three teeth. 2 a-2 f Trevelyana coccinea, p. 85. 2 a -2 d. First laterals of various shapes. Teeth from (2 e) middle and ( 2 / ) end of row. 3 a -3 c. Trevelyana ceylonica, p. 86. o m 3 a. First lateral tooth. 3 b. Teeth from the middle of a row. 3 c. Iliree teeth, seen from below and behind. 4. Trevelyana crocea, p. 87. P la t e IV . Figs. l a - 1 c. Trevelyana bicolor, p. 89. . 1 a. Lateral view of living animal, with the liver (the blackish tint) showing through the translucent body-wall. lb . Ventral view of crawling animal, showing the proportions of the foot^and some of the internal organs through translucent body-wall. 1 c. Gills as seen fully expanded. Figs. 1 a and 1 b are X 5. 2. Nembrotha cristata, p. 90. Middle of radula. 3a-3d. Nembrotha affinis, p. 92. _ 3 a, dorsal and (3 b) lateral views of living animal. 3 c, median and (3 d) first lateral teeth. 4. Marionia levis, p. 94. 5. Median teeth of (5 a) Hornella digitata (p. 101), (5 b) 13. excepta (p. 102), and (5 c) JB. simplex (p. 103). |
