viii PREFACE 



yet to be traced by entomologists. Measurements are given in every 

 case in millimetres (25 mm. = 1 inch), the first dimension being the 

 length of the fly, and the second the expanse of wings. For various 

 reasons it has not been found possible to reproduce the specimens on 

 one uniform scale: the same difficulty was met with by Dr Michael 

 in illustrating the Oribatidae. 



E. K. PEARCE 



BOURNEMOUTH 



June 191 5 



