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Show 1 9 0 3 .] FROM EAST AFRICA AND ZANZIBAR. 2 5 5 The j aws were large, with a smooth cutting-edge. The radula consisted of a single series of 13 transparent yellowish teeth of the shape usual in the genus, viz., pectiniform, with large irregular denticles and small accessory denticles. It was sometimes hard to decide whether the rather small denticles should be considered main or accessory; but the average number of main denticles on each tooth was 10, and the largest number (in one case only) 13. The central nervous system was somewhat concentrated. The specimen was only partly dissected. A new species must, I think, be provisionally created for this animal, though the discovery of intermediate forms may perhaps render its retention unnecessary. In some ways it is itself a connecting- link between C. longicirrhcc and C. annulata, for the former is said to have 7, and the latter 5 denticles on each side of its teeth, whereas C. africana has 4, 5, 6, or 7 indifferently. It can hardly be C. annulata, for the difference in colour is too great, and besides there is much less bare space on the back. Neither can it be C. longicirrha, because ( 1 ) the coloration, though similar, is still distinct; (2) C. longicirvlia has the back bare up to the 7th row of cerata, and some of the cerata are very long, which is not the case here ; (3) the rhinophores are not perfoliate. This last point is of some importance for the characterisation of the genus. In the present animal the rhinophores were undoubtedly quite simple in life, and in alcohol they are wrinkled, though it is still possible to see that they are not really perfoliate. In C. longicirrha, Bergh says the perfoliations are 14 or 15 in number, and not deep. Of C. annulata he says that the rhinophores have 12-14 well-marked perfoliations, and that Garrett has wrongly represented them as simple. But in Semper's ‘ Reisen,' xvii. he states that C. annulata var. affinis has simple rhinophores, and gives as a generic character: " Die Rhinophorien scheinen nicht perfoliirt zu sein." I have not access to part ix. of his ‘ Beitrage zur Kenntniss der Aeolidiaden,' which perhaps explains the matter; but it looks as if the rhinophores are simple, but have a tendency to simulate perfoliations when preserved. P t e r a e o l id ia sem p er i. (Bergh, Beitr. zur Kennt. der Aeolidiaden, iii. p. 22, and in Semper's Reisen, Malac. Untersucli. vol. i. p. 18 (1870); under Flabellina.) Four specimens, which seem probably referable to this species, were dredged from 3 fathoms near Chuaka in July 1901. The body is very long, narrow, and vermiform, the largest individual being 5*5 centim. long and only 3 millim. broad. The ground-colour of the body in the living animal is brown, with opaque markings of very light green on the sides and back. The cerata are also dark brown, with numerous thin lines of the same green. The top of the head and the ends of the oral tentacles are opaque yellowish white. The lower* part of the tentacles browTn, with three rings of P roc. Z o ol. Soc.-1903, V o l . I. No. X V II. 17 |