4 PREFACE 



Mr. Eltringham's (9) papers deal with the direct evidence 

 on which the theories of mimicry and warning colours are 

 built. Mr. Marshall has kindly allowed me to include in 

 this volume his masterly and comprehensive survey (8) 

 of the recorded attacks of birds upon butterflies. It is 

 appropriate that the monograph should appear in this book, 

 for it contains an account of all the available material in 

 the Hope Department, and of many observations made by 

 Oxford workers. Furthermore, its appearance has been 

 called forth by discussions which in recent years have 

 arisen over the work of the Department. 



Important investigations upon the systematics of Ortho- 

 ptera, carried out or promoted by Mr. R. Shelford, appear 

 in the succeeding group of memoirs (10-18). Of these, 

 1 0-13 A are concerned with the Biattidae, a family on which 

 Mr. Shelford is the leading authority. Mr. Shelford has 

 also contributed one paper (14) on the Mantidae. Dr. Han- 

 cock, of Chicago, has contributed a further monograph (15) 

 on the Tetriginae, a peculiar group of grasshoppers 

 {Acridiidac), in the University Collections ; while Dr. 

 Achille Griffini, of Genoa, has written three valuable 

 papers (16-18) on the Oxford material belonging to the 

 Locustid genus G7yllacris. 



The section above described is followed by a series of 

 short papers extracted from ' The Entomologist's Monthly 

 Magazine'. Three of these (19-21) record Mr. Hamm's 

 very interesting observations on the courtship of Empid 

 flies, while one (22) contains his notes on the pursuit of 



