II. The Nudibranchiata of the Scottish National Antarctic Expedition. By 

 Sir Charles Eliot, K.C.M.G. Communicated by Sir JOHN MURRAY, K.C.B. 



(MS. received March 24, 1905. Head May 15, 1905. Issued separately June 9, 1905.) 



The nudibranchs collected by the Scottish National Antarctic Expedition comprise 

 only six species, but these include two new and interesting genera. 

 The species are 



1. Notaeolidia gigcis, gen. et spec. nov. 



2. N. purpurea, sp. nov. 



3. Tritonia appendiculata, sp. nov. 



4. T. pallida, Stimpson. 



5. Tritoniopsis brucei, gen. et sp. nov. 



6. Scyllaea pelac/ica, L. 



The Scyllaea was caught on the return voyage, in the Atlantic, 32 N., 33 W. ; Tritonia 

 pallida, off Dassen Island, forty miles north of Cape Town ; Tritoniopsis brucei, off 

 Gough Island, 40 20' S., 9 56' W. ; and the three remaining species in Antarctic 

 waters. 



The most remarkable point about the collection is the entire absence of Dorids. 

 The collection made by the Discovery, which has also been entrusted to me for ex- 

 amination, shows the same character, and contains only one Bathydoris,* but several 

 Aeolids and Tritonids (not the same as in this collection), one Doto and one Notaeolidia. 

 The results of Northern Arctic expeditions are similar. The Dutch " Willem Barent " 

 Expedition obtained five Aeolids and two Dendronotus ; the Danish " Ingolf " Expedi- 

 tion two Tritonids, two Dendronotus, seven Aeolids, one Bathydoris, one Doridoxa, and 

 only three normal Dorids out of a total of sixteen species. In the Tropics the pro- 

 portion is reversed. Semper's collection from the Philippines contained only five kinds 

 of Aeolids and fifty-four of Dorids. 



None of the animals appear to have been brightly coloured. Most were, as far as 

 one can judge, white or pinkish. N. purpurea is, as preserved, of a dull purple. In all, 

 eyes are either absent or minute. 



With these nudibranchs were two small holothurians (identified by Mr F. JEFFREY 

 BELL as young specimens of Psolus), which closely resemble Dorids superficially. It 

 is not clear that this resemblance is of any advantage to the animals, and it is probably 

 due to mechanical reasons. Both Psolus and Dorids are slug-like animals, of moderately 

 tough consistency, and possessing a clearly differentiated ventral creeping surface, and 



* A second Bathydoris has heeii sent to me since. 

 [REPRINTED FROM THE TRANSACTIONS OF THE ROYAL SOCIETY op EDINBURGH, VOL. XLI., PP. 519-532.] 



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