24 



Mr. A. H. Hamm, of the Hope Department, has thrown so 

 much light upon the courtship of the Empid flies. 



Results so surprising require abundant proof, and it will be 

 admitted by any one who studies the series that the material 

 both of Empidae themselves and the insects captured or 

 objects seized by them, is of immense extent and most care- 

 fully collected, embodying the results of a large number of 

 original observations and most ingenious experiments. The 

 whole of Mr. Hamm's researches were carried out in the 

 neighbourhood of Oxford. The great labour of labelling and 

 cataloguing was finished by Mr. Collins in time for exhibition 

 at the Entomological Congress in August, 191 2, where the 

 collection was studied with keen attention and interest. The 

 catalogue numbers — 591 in 1908, 771 in 1909, 718 in 1910, 

 and 969 in 191 1 — large as they are. give a very inadequate idea 

 of the material ; for the catalogue is of mounts rather than 

 specimens, of which many are constantly carried on a single 

 card. The collection includes many specimens captured and 

 presented by Mr. Hamm's son, Mr. C. H. Hamm. 



A part of the results has been already published in the 



"Entomologist's Monthly Magazine" for 1908, p. j8i, and 



3909, pp. 132 and 157 ; but the most novel and interesting 



observations and conclusions — those obtained with the genus 



Hilara — are made known for the first time in the following 



brief account of Mr. Hamm's gift. The full and detailed 



account awaits publication until numbers of obscure and 



minute insects — Dipterous captors and prey chiefly Dipterous — • 



have been satisfactorily worked out. 



The collection has been classified by Mr. Hamm so as to 



1 



illustrate his conclusions, the species being arranged in groups, 

 each representing a definite evolutionary stage in the use of 

 prey — first and lowest as food devoured by both sexes without 

 relation to pairing, then as a gift provided by the male and 

 devoured by the female during pairing, finally — as it were an 

 ornament or plaything — no longer eaten by the female, but 

 acting as a lure and a stimulus. In this last stage the prey is 

 often replaced by some vegetable fragment which is quite 

 unsuitable as food. The climax of this line of evolution is 



