Xll PREFACE. 



/ 



I must also specially thank Mr. Alfred Osten Walker 

 for his able guidance in many matters relating to this 

 work, and the Rev. Dr. Tho's. Wiltshire, F.L.S., the 

 Secretary of the Ray Society, for undertaking the la- 

 borious task of reading through my proofs and offering 

 valuable suggestions. 



With two exceptions all the illustrations have been 

 drawn by myself expressly for this work ; and the 

 reproductions by lithographic process have been pre- 

 pared with great care and fidelity by P. W. M. Trap, of 

 Leiden. Dr. Maxwell T. Masters, the Editor of the 

 c Gardener's Chronicle,' has kindly permitted the use of 

 the blocks illustrating yL//A/>v/x/>/x i><>iif<t</<>ii<i (Figs. 19, 

 20, p. 174) ; and the Rev. W. Wilks, M.A., Secretary 

 of the Royal Horticultural Society, the ten blocks 

 illustrating Plates A to E. Plate XI, fig. 7, showing 

 the marginal fringe of the pygidium of A*indiutux 

 perseae, is copied from Prof. Comstock's drawing 

 (Report 1880, pi. xii, fig. 3). The comparatively 

 recent discovery of five species of Diaspinae has necessi- 

 tated the illustrations of them accompanying the text ; 

 otherwise, they would have appeared in order upon the 

 lithographic plates ; but it was fully intended the 

 diagrams illustrating the various parts of the Diaspinre 

 should accompany the letterpress concerning them. It 

 was thought by so placing them the student would 

 be saved the necessity of cross-reference to plates. 



R. N. 



GROSVENOR MUSEUM, 



CHESTER ; 



October I*/, 1901. 



