RECENT LITERATURE. 283 



The author has had it in preparation for many years, and we gather 

 that it would have been issued in 1917 but for the Great War. 



The whole of the slides and letterpress are the work of Mr. Pierce ; 

 the plates, very excellent ones, are from the drawings of Mr. 

 Metcalfe. 



In previous volumes the genitalia were drawn to scale, but in the 

 case of the Tortricidce this process would have so reduced the figures 

 of the smaller species their value would have been greatly lost ; the 

 drawings have therefore in this instance been kept of a fairly uniform 

 size, so that the different and characteristic points in even the smallest 

 species might be shown. 



In the arrangements of the drawings on the plates the male organs 

 are on the right, those of the female on the left. This will no doubt 

 be apparent to most students, but in each future volume it might be 

 better to give a short explanation as to the precise meaning of the 

 various figures. 



The author has gone a step further than in previous volumes, and 

 has introduced a scheme of classification based upon the characters 

 of the genitalia only. 



This method is interesting, because it shows the relations of the 

 various species to each other from the point of view of these organs ; 

 but it produces some strange bedfellows, and widely separates species 

 that have in the past considered themselves nearly related, and that 

 will in all probability continue to be regarded as such in the future. 

 The author, however, admits that the final classification must be based 

 upon a study of all the characters — a view with which we certainly 

 agree. 



Mr. Pierce states that the most arresting result of his study of the 

 genitalia of the Tortricida? is the way the species fall into clearly 

 defined groups, and that it is possible at once to place a species in 

 the group to which it belongs ; but that these organs shed very little 

 light on the historic relationship of the groups. He considers that 

 with respect to position there is a connecting link with the Geomctridac 

 where the characteristic hinged and much curved penis of the Tortri- 

 ciclae appears in the Ghesiadinae, notably in the case of Anaitisplaijiata 

 and in Odezia atrata. When we come to specific differences, these, 

 although constant, are sometimes extremely small, yet within a group 

 it is possible to secure a perfectly natural sequence. 



In classifying in accordance with the characteristics of the genitalia, 

 the author has worked out the genera with the aid of Fernald's 

 Genera of the Tortricidae and their Types ; he does not, however, 

 create new names for genera or types in instances in which he has 

 been unable to trace any generic name, but has left blank spaces, in 

 order to avoid creating superfluous names for genera which may 

 already exist ; he is to be thanked and congratulated on this 

 decision. 



Mr. Pierce states that in the course of the investigations of Mr. 

 Metcalfe and himself they have added six new species to tho British 

 List, though we think there is a doubt if all of these will permanently 

 stand. On the other hand he cannot find any difference in 

 the genitalia between no less than five pairs of species at present, 

 generally regarded as distinct, and with good reason in the majority 



