1903.] FROM EAST AFRICA AND ZANZIBAR. 255 



The jaws were lai'ge, with a smooth ciitting-edge. The i-adula 

 consisted of a single series of 1 3 tiansparent 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 oi- accessory ; but the avei-age number of main denticles on 

 each tooth was 10, and the largest number (in one case only) 13. 

 The centi'al 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 discoveiy of intermediate forms may perhaps 

 render its retention unnecessaiy. In some ways it is itself a con- 

 necting-link between C. longicirrha and G. annulata, foi- 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 indifi'erently. It can 

 hardly be C. annulata, foi- the difference in colour is too great, 

 and besides there is much less l)are space on the back. Neitlier 

 can it be C. longicirrha, because (1) the coloration, though similar, 

 is still distinct ; (2) C. longiciy-rha 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 G. longicirrha, Bergh says the perfoliations are 14 or 15 in 

 number, and not deep. Of G. anmdata he says that the rhino- 

 phores have 12-14 well-marked perfoliations, and that Garrett has 

 wi-ongly represented them as simple. But in Semper's ' Reisen,' 

 xvii. he states that G. annulata vai'. affinis has simple rhinophores, 

 and gives as a geneiic character : " Die Rhinophorien scheinen 

 nicht pei-foliirt zvi sein." I have not access to part ix, of his 

 * Beitiage zur Kenntniss der Aeolidiaden,' which perhaps explains 

 the mattei- ; but it looks as if the rhinophores are simple, but have 

 a tendency to simulate perfoliations when preserved. 



Pteraeolidia semperi. 



(Bergh, Beitr. zur Kennt. der Aeolidiaden, iii. p. 22, and in 

 Semper's Reisen, Malac. Untersuch. vol. i. p. 18 (1870); vuider 

 Flahellina.') 



Foui- 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 

 veiy 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 brown, with three rings of 



Proc. Zool. Soc— 1903, Vol. I. No. XVII. 17 



[7] 



