1904.] FROM EAST AFRICA AND ZANZIBAR. 105 



from various points. The external characters are those o£ the 

 genus. 



The mouth-parts on the whole resemble those of PL 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 paiullel 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 con- 

 stitute provisional specific rank, though it is quite possible that 

 the form may ultimately prove a mere variety of PI. striata. 



EXPLANATION OF THE PLATES. 



Plate III. 



Figs. 1 a-1 </. Notodoris minor, p. 84. 



la. Lateral view of living animal. 1 b. Dorsal view of living auimal. 

 1 c. Hinder part of body with tlie valves raised and spread. 1 cl. Gills 

 with the valves removed. 1 e. Ventral view of anterior part of body. 

 If. Glans penis. 1 g. Three teeth. 



2 a--'2if. Trevelyana cocciiiea, 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 cei/lonica, p. 86. 



3 a. First lateral tooth. 3 h. Teeth from the middle of a row. 3 c. Three 

 teeth, seen from below and behind. 



4. Trevelyana crocea, p. 87. 



Plate IV. 



Figs. 1 rt-1 c. Trevelyana hicolor, p. 89. 



1 a. Lateral view of living animal, with the liver (the blackish tint) 

 showing through the translucent body-wall. 1 h. 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 h are X 5. 

 2. Nemhrotha cristata, p. 90. 



Middle of radula. 

 3 rt-3 d. Nemhrotha affinis, p. 92. 



3 a, dorsal and (3 b) lateral views of living animal, 3 c, median and 

 (3 d) first lateral teeth. 



4. Ilarionia levis, p. 94. 



5. Median teeth of (5 a) Bornella digitata (p. 101), (5 b) B, e^cejjfa (p. 102), 



and (5 c) B. simplex (p. 103). 



