PREFACE. 



THE delay that has occurred in completing this work has 

 been to a great extent unavoidable. Professor Westwood's 

 death and the time which elapsed before his successor was in 

 due course appointed, and the alterations and improvements 

 that were subsequently made in the Hope Department of the 

 University Museum, closed the collection of insects for many 

 months, and when I was able to recommence the work I had 

 many other interests in hand, and was able to give only a 

 portion of my time to it. 



The Pyralidina were practically completed in 1893, and the 

 Geometrina in 1894. I left the Noctuina to the last, so that 

 I might take advantage of Sir George F. Hampson's classi- 

 fication ; vol. ii. of his Moths of India being then in the press. 

 Finally, I decided to wait for the conclusion of his revision of 

 the whole of the Indian Heterocera before going to press. 



I have been very careful to keep separate, under their dis- 

 tinctive names, the various local and varietal forms of each 

 species. To mix such forms up together as synonyms of the 

 parent species is to do an absolute injury to science, rendering 

 a collection comparatively useless for the purposes of refer- 

 ence. We thus lose one chief interest of our subject, the 

 inquiry into the subsequent fate of a parent species as it 

 branches off into the various sub-specific local and varietal 

 forms, some of these again becoming established, and form- 

 ing parent species. 



