no other work has such fulness of treatment 

 been given, nor is it easy to see where any- 

 thing essential to the history of a name has 

 been omitted. As the { index ' includes up- 

 ward of 4,500 names, the immense amount of 

 labor involved in its preparation is evident, 

 while no similar work is to be compared with 

 it in fulness of detail and consequent useful- 

 ness. Of these 4,500 names, it is stated that 

 over 400, or 10 per cent., prove to be preoc- 

 cupied, and of these latter 'about 150, or nearly 

 40 per cent., are homonyms in the class Mam- 

 malia ' (p. 953). 



In Part II., ' Family and Subfamily Names,' 

 the treatment is necessarily different, in ac- 

 cordance with the requirements of the case. 

 Here the name, author, date and the order to 

 which it is referred are stated, followed by a 

 reference to the place of first use, with sec- 

 ondary references to its variants, if any, and 

 modified uses as regards the rank of the group. 

 The arrangement is, of course, alphabetic, and 

 the index proper is preceded by several pages 

 giving the history of the origin and use of 

 such names, particularly in reference to the 

 final adoption of the terminations idee and 

 ince, indicating respectively families and sub- 

 families. There is also a summary of the 

 rules that have been proposed by different 

 nomenclatural codes in relation to these 

 groups, and illustrations of the difficulty of 

 applying these rules. 



Part III., ' Index of Genera Arranged Ac- 

 cording to Orders and Families/ has been 

 prepared to show ' what names have been used 

 in a certain group, why a name is unavailable, 

 or whether any published name is available for 

 one which is preoccupied.' The arrangement 

 is here alphabetic, first as regards orders, and 

 secondly as respects the families, subfamilies 

 and genera, within the orders. The classifica- 

 tion adopted is that of Flower and Lydekker 

 in ' Mammals, Living and Extinct ' (1891), 



