327 



NUDIBRANCHS FROM NE^y ZEALAND AND THE FALKLAND 

 ISLANDS. 



By Sir C. N. E. Eliot, K.C.M.G. 



Read IWi June, 1907. 



PLATE XXVIII. 



These notes on New Zealand nuclibranchs are based partly on material 

 kindly sent to me by Mr. Henry Suter and Mr. Charles Cooper, and 

 partly on P. Abraham's type-specimens preserved in the British Museum 

 and most courteously placed at my disposal by Mr. E. A. Smith. 

 Abraham described very imperfectly a number of old specimens. In 

 some cases they are so decayed and the descriptions so deficient in 

 definitely formulated characters that his names can be set aside. In 

 other cases such as Doris musctda, B. lanuginata, etc., the characters 

 of the labelled specimens, if not those given in the descriptions, are 

 sufficiently clear and the names must be respected. 



In the nudibranch fauna of both New Zealand and the Falkland 

 Islands one is struck by the fact that similar or identical forms occur 

 in the Pacific as well as in the Atlantic on both sides of the equator 

 outside the tropics, although they are absent or scarce within the 

 tropics. Thus Acatithodoris pilosa is recorded from the North Atlantic, 

 the North Pacific, and New Zealand, and ^olidia papillosa (or 

 jE. serotina, a very similar form) from the North Atlantic, North 

 Pacific, and Falkland Islands. But I think that in cases where the 

 identity is not absolute, it is better to create or recognize separate 

 species. Considering how greatly preserved nudibranchs change their 

 colour and shape, a considerable assumption is always involved in 

 identifying an alcoholic specimen from the southern hemisphere with 

 a species from the Nortliern Atlantic, and, if any points of difference 

 are found, it seems to me safer to emphasize them, though they may 

 be minute. Identifications of northern and southern species are 

 generally accepted without criticism and made the basis of important 

 theories. The creation of a new species challenges re -examination 

 and really contains less of the speculative element. 



Nevertheless, there can be no doubt that these southern seas contain 

 a considerable number of forms which are either specifically identical 

 with northern forms, or so closely allied to them, that they must be 

 supposed to be sprung from the same immediate ancestors. The same 

 is true of Antarctic Pteropods (see my report on the collection made 

 by the 'Discovery'), but the coincidence is less noticeable in the case 

 of Antarctic nudibranchs, which off'er many new types that have not 

 yet been found elsewhere.' For drawing any general conclusions the 

 nudibranchs of New Zealand should probably not be regarded as 



Archidoris tuberculata is recorded from 65° 5' S. (Vayssiere), and perhaps Doto 

 antarctica, Eliot, is Doto fragilis (Forbes). 



