viii PREFACE 



types of sea-shore themselves afford scope for all kinds of 

 interesting faunistic and ecological contrasts. 



While the ecological aspect of the sea-shore has attracted 

 a great number of research workers, from the point of view 

 of teaching it would not seem to have received an equivalent 

 amount of attention. It cannot be doubted that if a student 

 confines himself, when on the sea-shore, purely to collecting 

 and labelling species he is not obtaining a tithe of the benefit 

 that his visit is capable of affording him. Consequently in 

 planning this work, one of our chief ambitions has been to 

 stimulate a wider interest on the part of the student by 

 depicting for him something of the wonderfully vigorous and 

 many-sided nature of the struggle for existence between 

 tide-marks, and by drawing his attention to some of the 

 innumerable problems connected with shore animals which 

 still await investigation. 



We have had no wish to treat our subject exhaustively. 

 For the most part we have confined ourselves to those 

 British species with which we have first-hand acquaintance. 

 To have foregone, however, all mention of foreign and, in 

 particular, of tropical forms, would be to have excluded 

 phenomena of the very greatest interest to our theme. It 

 frequently happens, for instance, that a habit or an associa- 

 tion which is only slightly developed on our own shores has 

 been brought to a high degree of specialisation elsewhere, 

 especially in warmer seas. Consequently, we have not 

 hesitated to give cases of this kind as large a measure of our 

 attention as space allowed. For analogous reasons, while 

 our main concern is with species occurring between tide- 

 marks, we have not infrequently extended our survey to 

 include forms which more properly belong to the waters 

 beyond the Laminarian zone. 



In preparing this account of the life of a marine area we 

 have been deeply conscious of our debt to the many 

 naturalists whose rich discoveries have been so freely at our 

 disposal. As far as has been in our power we have re- 

 sponded to this obligation by the care we have given to the 

 citation of appropriate authorities in the text. In our list of 



