morants, and Herons^ by Dr. Sharpe ; and vol. xxvii. the 

 Geese, Ducks, and the remainder of the Class of Birds, 

 by Count T. Salvadori. Thus, as these naturalists are all, I 

 believe, busily engaged on the compilation of their respective 

 tasks, we may look forward to the completion of this 

 arduous undertaking within a definite period — say, two or 

 three years from the present time. 



The point I wish now to impress upon my brother orni- 

 thologists is the great importance and advantage of an index 

 volume to close the series. . It has been suggested, I am told, 

 that an index of the genera would be sufficient. ' An index of 

 genera would be, no doubt, most useful — in fact, I have 

 had such an index of the volumes already issued prepared 

 for my own use; and very handy indeed do 1 find it. But 

 to this should certainly be added a second index to all 

 the specific names referred to in the twenty-seven volumes of 

 the work. Such an addition would no doubt be somewhat 

 bulky, as I find that the average number of pages taken up 

 with the index of each volume is about 2.2, which multiplied 

 by 27 would make a volume of nearly 600 pages for the final 

 Index : — 



Average number of pages of Index in the 23 published 

 volumes of B.M. Cat. Birds 22 



Total number of pages of Index in the whole 27 volumes 594< 



But there can be no doubt that such an index would be 

 of surpassing value to the working ornithologist ; and as it 

 might be easily compiled from the indexes already published, 

 the labour of making it would not be serious. Still more 

 complete and still more useful would such an index be, if, 

 after the final volume of the Catalogue, an additional volume 

 were prepared in which all the names of species described 

 since 187I: (when the Catalogue was commenced), and not 

 already recorded in the diS'crent volumes, were enrolled, with 

 references to each of them. If this addinioual volume were 

 also indexed in the ' General Index ' the result would be a work 

 of reference to the class of Birds much more complete and of 

 far greater general usefulness than the late G. R. Gray's 



