148 Transactions of the Royal Canadian Institute 



to fill, owing to the impossibility of preserving either the natural form 

 or colour of these animals. This alteration in appearance is so striking 

 in some cases that the species cannot be recognised without dissection 

 and even then maybe uncertain unless the preservation is gcod. For that 

 very reason a completely satisfactory account of any form necessitates 

 the examination of living specimens; and the establishing of a colour 

 variety such as Bergh has done (3, p. 172) in the case of Diaulula sandie- 

 gensis var pallida on preserved material is a hazardous proceeding and 

 can only be justified by subsequent reference to living material. Indeed, 

 if I may venture to criticize one who is perhaps the foremost authority 

 on this group, Bergh was inclined to make new varieties or even species 

 for forms found on this coast without sufficient grounds for so doing. 

 In certain cases the colour entirely disappears after a few hours and after 

 some time has elapsed specimens taken together and preserved together 

 will have a very different appearance, owing presumably to the different 

 physiological conditions of the individual at the time of fixing. 



The colour of living members of the same species is subject to con- 

 siderable variation and in some instances the colours of specimens 

 collected here differ from those from Monterey described by MacFarland 

 and to this I have called attention when necessary. It is not meant to 

 imply that MacFarland's account is inaccurate, but simply that the 

 specimens obtained here are somewhat different. There is of course a 

 distinct difference in the local environment, for on the whole there is 

 considerably more sand at Monterey Bay than anywhere I have collected. 

 This however does not appear to have any general affect on the nature of 

 thie colour difference for while in some species, e.g., Diaulula sandiegensis 

 it is considerably darker, in others, e.g., Cadlina marginata it is much 

 lighter. 



Material. 



The following list is based upon material collected from the Biological 

 Station, Nanaimo, B.C. The preserved material in the station was 

 kindly placed at my disposal by Dr. C. McLean Fraser who had collected 

 most of it, the rest being a few specimens obtained by Professor J. Play- 

 fair McMurrich and the late Rev. G. W. Taylor. In adddition I have 

 collected a number of species and examined a large number of individuals 

 while still living, so that unless otherwise stated the descriptions are 

 based upon living material and the preserved specimens have been 

 utilized for data regarding distribution. The living material has enabled 

 me to give colour notes for certain species that have not been available 

 previously. In some cases specimens in spirit or formalin have been the 

 only ones examined and the account of their colour has been taken from 



