PREFACE. Vll 



An imperative but most agreeable duty remains that of thanking those kind 

 friends who have rendered me such important services during the progress of this 

 work. And first Mr. Doubleday, through whose hands every sheet and every column 

 has passed. Many omissions have thus been supplied and many errors expunged. 

 An almost perfect blank has hitherto existed as to the times of appearance of our 

 Lcpidoptcm in the perfect state, and my own experience was insufficient to supply this 

 blank. Although for many years I was an assiduous collector of insects, I never gave 

 that especial attention to Lepidoptcra which they have received at the hands of my 

 friend. The collections of Diptera, Hijmenoptem, Coleoptera, and Ncuroptera under my 

 care, attest the fact that my attention has been equally divided amongst all classes of 

 insects, and it is next to impossible to acquire anything approaching a perfect know- 

 ledge of the times of appearance of every species. Mr. Doubleday has abundantly 

 made up for my shortcomings in this respect, and has supplied me with information 

 which, in many instances, has never before appeared in print. Then again the 

 Eupithecice, and the Lcucaniche have undergone a complete revision at his hands ; he 

 has found it necessary to alter a few names, generic as well as specific, and to institute 

 a few new combinations. 



The idea that at any given period we can assert that we have reached the 

 ultimatum of knowledge appears to me utterly untenable ; and I feel assured that the 

 assiduity of future labourers in this delightful field, will lead to the addition of many 

 facts I have omitted, and the emendation of many errors I have allowed to pass. 

 Were it not so were there no Excelsior the study would lose one of its principal 

 charms. The slight inconvenience caused by altering a name, or amending a descrip- 

 tion, is abundantly compensated by the advantage of substituting truth for error. 

 In expressing these opinions to a very candid friend, he at once enquired, " How do 

 we know that even these amendments are final ? What security have we that 

 amendments themselves will not require emendation?" I answered, "There is 

 certainly no such security ; and I desire none : I have no more power to affix limits 

 to knowledge than to arrest the growth of an oak ; and I regard with no feelings of 

 apprehension the advent of some future Doubleday who may detect errors in the 

 labours of him who is happily still amongst us." 



To Mr. Bond my especial thanks are also due : with a liberality equal to 

 Mr. Doubleday's he has placed the free use of his immense collection at my 

 disposal ; he has repeatedly invited me to select specimens, even when unique, 

 for the purpose of figuring ; and by this means I have been enabled to give 

 accurate representations which it would have been otherwise quite impossible to 

 obtain. 



To Mr. Birchall I am indebted for the loan of some of his choicest specimens ; 

 and for the expression of his opinions on questions of great interest and importance ; 

 more particularly in the genus Dianthceda, with which, in a state of Nature, he has a 

 more practical acquaintance than any other British entomologist : the distance of his 

 fine collection from London has been the only bar to my availing myself far more 



