NUDIBRANCHS OF THE VANCOUVER REGION I47 



NUDIBRANCHIATE MOLLUSCA FROM THE VANCOUVER 



ISLAND REGION. 



By Chas. H. O'Donoghue, D.Sc, F.Z.S. 

 Professor of Zoology, University of Manitoba. 



The marine fauna of the coasts of British Columbia is particularly 

 rich and varied and yet, so far, no description of the Nudibranchiata of 

 this region has been published. Indeed this group of animals has only 

 received comparatively little attention on the Pacific coasts of North 

 America in general. One result of this is, that the number of species 

 recorded is not so large as from the western coasts of Europe and this 

 is probably due to a lack of workers and not to a lack of material. It 

 seems advisable therefore to provide a diagnosis of the species so far 

 collected in sufficient detail to render their recognition easy and certain. 

 This will serve as a basis and indeed as a necessary preliminary for future 

 work on distributional, bionomic or developmental lines. It is rather 

 fuller than is necessary in some groups of animals since Nudibranchs 

 appear to be subject to a wide range of individual variation in the matter 

 of size, colour, etc., and practically none possess definite, easily recog- 

 nisable characters that enable them to be distinguished from allied 

 species. The following list cannot claim to be complete, but it is hoped 

 that at any rate it includes all the commoner forms to be found within 

 the area available from the Dominion Biological Station, Nanaimo, 

 Vancouver Island, British Columbia. 



The pioneer work on the Californian coast was done by Cooper (5), 

 Fewkes (8) cind Steams (13), but in all cases their descriptions are 

 indefinite and in some instances so much so that it renders the recog- 

 nition of the species a matter of difficulty if not impossibility. Bergh 

 (2 and 3) in 1879, 1880 and 1894 described a number of forms not only 

 from the Californian coast but also from Alaska, but unfortunately all 

 of his work was done upon preserved specimens and these are always 

 altered as a result of the preservation. Apart from a note on some 

 Californian species by Cockerell and Eliot (4) the recent work on the 

 same area has been done by MacFarland. This author in a series of 

 papers (lo, ii, 12) has described certain genera in a most satisfactory 

 manner. In his work he expresses regret at the lack of adequate coloured 

 drawings of the different species of the Pacific, a gap that he has done much 



