Of the Plates, IX. to XIV. have been prepared for me from the original 

 drawings made by Mr. Matthews with his well-known artistic skill and accuracy, 

 the figures having been most carefully and satisfactorily transferred to zinc by 

 Mr. J. Collin, of Newmarket, and I have to thank him for the trouble and pains 

 he has taken to make them accurate copies of the originals. Plate XV. is a 

 photo-lithographic reproduction of that published in Mr. Mattiikws's 'Essay on 

 Hydroscapha,' and has been carefully prepared for me by Messrs. West, Newman, 

 and Co., in order to complete the illustration of all the new genera discovered 

 since the publication of the ' Trichopterygia Illustrata et Descripta ' in 1872. 

 The Plates have unfortunately been numbered IX. to XV. consecutively, in 

 continuation of those in the ' Monograph of the Corylophidse and Sphseriidse,' 

 as it was at first intended to issue the two works as one volume. 



I must also express my thanks which are due to Mr. G. C. Champion, 

 Mr. C. 0. Waterhouse, and Mr. George Lewis, for the assistance they have 

 given me, and more especially to Mr. 0. E. Janson, who has been of invaluable 

 service to me in verifying and obtaining references to the literature, reading 

 proofs, preparing the Index, and other matters in connection with the printing and 

 publication. 



PHILIP B. MASON. 



Burton-on-Tren] 

 July, 1900. 



