PREFACE ix 



authorities the names of Prof. W. C. M'Intosh — the " doyen " 

 of British faunists — and of Prof. W. A. Herdman recur with 

 particular frequency, and we venture, in consequence, to take 

 the opportunity of offering to these veteran workers in the 

 domain of marine biology a special tribute of admiration and 

 respect. 



We have also great pleasure in expressing our deep 

 gratitude to Prof. J. Arthur Thomson, who has not only 

 placed his profound knowledge of biology unreservedly at 

 our disposal but has helped us in every conceivable way. 

 His kindly criticism has saved us from many blunders and 

 his unfailing courtesy and encouragement to one of us when 

 associated with him as his assistant are among our hap- 

 piest recollections. Dr. Wemyss Fulton and Dr. H. C. 

 Williamson, by placing the library and laboratory at Nigg 

 at our disposal, gave us valuable assistance. The visit of 

 one of us to the Marine Biological Station at Millport was 

 made especially pleasant and profitable by the kindness 

 of the Superintendent, Mr. R. Elmhirst, who, in addition, 

 gave us much help in preparing the survey of Balloch Bay 

 which appears in the Appendix. 



With regard to illustrations, we are indebted to Messrs, 

 Macmillan for the loan of the fine block illustrating variation 

 in Purpura lapillns ; to Prof. J. F. Gemmill and the Council 

 of the Royal Society for the illustration of the mode of 

 locomotion of the sea-urchin ; to Mr. L. A. Borradaile and 

 the Syndics of the Cambridge University Press for the 

 drawing of Melia tessellata ; to Prof. A. Meek and Messrs. 

 Arnold for the drawing of a stickleback's nest ; to Dr. W. 

 Collinge and the editor of "Nature" for the diagram 

 dealing with the food of the black-headed gull ; to Messrs. 

 Padgett, Leigh-on-Sea, for the illustrations of the cockle 

 industry. Prof. James Johnstone kindly lent us the photo- 

 graphs of pelagic forms reproduced on Plate III and of the 

 crab larvae on Plate XIV ; and Mr. B. Storrow those of 

 timber bored by Teredo and Xylophaga. Mr. Storrow also 

 lent us the illustration of the starfish Solaster endeca in the 

 act of spawning. Dr. Macgregor Skene kindly undertook 



