27 



labelled with the hour and minute at which the different 

 samples were secured. 



Mr. Hamm's admirable experiments also enabled him to 

 determine that the females carry the objects provided by the 

 males ; for although they are never retained when the pairs 

 are captured, the white florets or the yellow stamens can be 

 seen hanging from the lower Hilara of each flying pair, and 

 the lower is invariably the female. 



The climax is reached in the males of certain species of 

 Hilara which envelop the prey or other minute object in 

 a cocoon, varying greatly in complexity, but in the most 

 extreme cases of striking beauty and regularity. The cocoon 

 is spun upon the wing, so that the method of its construction 

 cannot be followed. Captured individuals are often found to 

 have extruded a viscid globule — probably the material out of 

 which the cocoon is spun. There can be little doubt that in 

 these extreme cases it is the cocoon itself which acts as 

 a stimulus to the female, although the minute and almost 

 invisible object usually enclosed in it, but sometimes dropped, 

 is the stimulus which incites the male to spin. Cocoons that 

 have been dropped, probably after pairing, are constantly 

 picked up and used over again by other males. 



These novel and surprising conclusions, obtained as the 

 outcome of Mr. Hamm's energy, resource, and power of 

 accurate observation, are illustrated and confirmed by an 

 immense mass of mounted material, catalogued under 355 

 numbers in 19 10 and no less than 660 in 191 1. 



The collection of British Diptera greatly benefited, as in 

 many previous years, by the generous kindness of Col. J. W. 

 Yerbury, no less than 740 specimens having been catalogued 

 and incorporated. The dates of capture range from 1894 to 

 19 10, and localities from the following counties are repre- 

 sented : — Inverness, Nairnshire, Perthshire and Sutherland, 

 Herefordshire, Gloucestershire, Devon, Dorset, Hampshire, 

 Kent, Surrey, Essex, Suffolk. Many Diptera from a few 

 localities in N. Wales and from Porthcawl in S. Wales are 

 also present. The species belong principally to the Antho- 

 ■ viyidae % Sepsidae, Gcomyzidae, Ep/iydridae, Drosophilidae, and 



A 8 



