ADVERTISEMENT. 



J. HE publication of the concluding- volumes of 

 the cc Introduction to Entomology" has been un- 

 avoidably delayed by the continued ill health of 

 one of the Authors, which has devolved upon the 

 other a considerable increase of labour, and de- 

 manded a greater expenditure of time than would 

 otherwise have been required : for though Mr. 

 Spence put every facility in Mr. Kirby's power, 

 and had drawn up a rough copy of every Letter 

 belonging to his department ; yet, as most of 

 them had been written several years ago, many 

 curious facts,, and a great variety of interesting- 

 information subsequently derived from various 

 sources, were necessarily to be inserted, and the 

 whole to be prepared for the press. 



When the thousands of objects that were to be 

 examined, and many of them repeatedly, in com- 

 posing the Letters on the External Anatomy of 

 Insects, are considered, it will not appear sur- 



