1904.] O^ NUDIBRANCHS FROM EAST AFRICA AND ZANZIBAR. 83 



[From the Proceedings of the Zoological Society of London, 



1904, vol. ii.] 



[Published October 1, 1904.] 



On pome Nudibranchs from East Africa and Zanzibar. 

 Part V.^ By Sir C. Eliot, K.C.M.a., late H.M. Com- 

 missioner for the East African Protectorate, F.Z.S. 



(Plates III. & IV. t) 



In my last two papers I treated of the Dorididse Crypto- 

 branchiatse as a group, but no systematic importance is to be 

 attached to the order in which the species now to be described are 

 arranged. 



Pteraeolidia semperi. — Since writing my description of this 

 species in my second paper (P. Z. S. March 17, 1903, p. 255), I have 

 i-ead Prof. Bergh's account of JVossis, characterised by a lateral ridge 

 similar to that found in some of my specimens (' Opisthobranchiata 

 of Danish Expedition to Siam,' 1899-1900, p. 52), and accordingly 

 carefully re-examined them to see if they should not be referred 

 to this new genus. It appears that they should not. The radula 

 is uniseriate, consistently of 18 teeth, and the same in the 

 specimens which have and those which have not the lateral ridge. 

 It therefore seems clear that the i^idge is found in the genera 

 where the radula is uniseriate as well as in those where it is 

 triseriate, and, further, that in alcoholic specimens, at any rate, it 

 may be present or absent in the same species. 



* For Part IV. see P. Z. S. 1904, vol. i. p. 380. 

 t For explanation of the Plates, see p. 105, 



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