PREFACE. Xlll 



am also indebted for much kind classical assistance in the 

 preparation of the nomenclature. 



And lastly, I must not omit expressing my acknow- 

 ledgements to Mr. W. Lens Aldous, for the exceedingly 

 accurate and beautiful delineations, by the aid of the micro- 

 scope and camera-lucida, of the delicate and frequently com- 

 plex tissues which illustrate this work. 



I fear that, in the performance of this agreeable duty of 

 thanks to the numerous friends who have so generously 

 assisted me, I may have inadvertently omitted the mention 

 of some who have favoured me with specimens or other 

 assistance, but to those I have named, and to all who have 

 contributed either information or specimens, 1 beg to pre- 

 sent my most sincere thanks. 



