1904.] FROM EAST AFRICA AND ZANZIBAR. 289 



The radula consists of a single series of teeth of the form usual in 

 the genus, with a moderately large central cusp and six denticles on 

 each side, of which the innermost and outermost are the smallest 

 and the median the largest. The jaws bear a single series of 

 35 rather irregular denticles, The verge is armed with spines. 



This appears to be a new species of Facelina, but I have not had 

 an opportunity of seeing the description of F. cyanella (Couth.), 

 which Bergh refers to this genus with a query. 



Phyllodesmium hyalinum Ehrenb, 



[Ehrenberg, Symbolae Physicse, series prima, 1831 ; Bergh, 

 ^' Anatomisk Undersogelse af Ph. hyalinum" Naturhist. Foren. 

 Yidensk. Meddelelser, I860.] 



One specimen dredged in about 10 fathoms near Wasin, 



The notes on the living animal are as follows : — " About one inch 

 long. Body semiopaque, pure white. Rhinophores and tentacles 

 ditto. Rhinophores slightly annulated, shorter than the tentacles. 

 Cerata very long and opaque, so that the liver is not visible ; 

 whitish violet in colour ; their upper halves and the whole length 

 of the sides are covered with low rounded projections, between 

 which dark-brown pigment is found. The first groups of cerata 

 are almost at the side of the rhinophores, and consist of only two 

 cerata on each side. The remaining cerata are set in seven pairs 

 of clumps of four each, and there is a space between the second 

 and third pairs of ckimps. The cerata are somewhat flattened." 



The preserved specimen is 10"5 mm. long and 3 broad, with a 

 thi-ead-like tail. Relatively to the size of the animal, the cerata 

 are enormous, the largest being 8 mm. long. They are flattened, 

 rather convex on the outer and concave on the inner face. The 

 edge all round is marked by a line of knobs, which are, however, 

 miore numerous at the top than at the bottom. On the outer side 

 the whole surface of the upper half is covered with similar knobs. 

 On the inner side the surface is mainly smooth except at the edges, 

 but at the very top there are a few knobs. The cerata are largest 

 on the inside, and gradually decrease outwards. The smallest 

 appear to have no knobs. The larger are easily detached, and 

 hence the arrangement of groups was not easy to see in the pre- 

 served specimen, but it appeared to have been as described in the 

 notes on the living animal. The rhinophores are short and thick, 

 set close together, and annulate. The tentacles are longish and 

 curved. The foot is grooved anteriorly, and produced into mode- 

 rately long but not conspicuous tentacular angles. The anal 

 papilla is latero-dorsal, just behind the rather large pericardial 

 prominence. The genital openings are under the rhinophores. 



The jaws bear five or six coarse denticles, of which three are 

 very large indeed, the others smaller. The radula consists of 

 sixteen colourless teeth, bearing between 30 and 40 denticles on 

 each side. The shape is much as in Bergh's plates {I. c), but the 

 denticles are rather longer, 



Proc. Zool. Soc— 1904, Yol, II, No, XIX. 19 



