153 



on the Cordiilines (1906) and three on the .^ischnines (1908-9), 

 by M. RÉNÉ Martin, and ftve on the LibelluUnes (1909 onward) 

 by Dr. F. Ris. 



The fascicules on the CorduUnes and the ^Eschnines are 

 essentially expansions of de Selys's own publications on these 

 groups, with the addition of such genera and species as were 

 unknown at those earlier dates. That on the Cordulines has 

 given rise to two attempts to establish a more natural classifica- 

 tion of this subfamily by Williamson (1908) and by Needham 

 (1908) respectively, based on venation, and to still further 

 modifications, in which both larval and adult characteristics are 

 taken into account by Tillyard, in an excellent Monograph of 

 the genus Synthemis (1910), and in later articles (191 1). 



The fascicules on the Libellulines represent an enormous 

 amount of work on the part of their author, Dr. Ris, not only 

 because of the very great number of forms which this subfamily 

 contains, but also because of the inherent difíiculties of the 

 group itself. De Selys had never outlined a classification of the 

 Libellulinie, the only subfamily which even his long life did not 

 enable him to reach. Although Brauer (1868), Kirby (1889), 

 and Karsch (1890) had revised the genera from time to time, no 

 one had attempted to describe all the species and refer them to 

 their genera in one monographic treatment. This is the task 

 which Dr. Ris has on his hands and for which he receives the 

 hearty thanks of Odonatologists everywhere. 



It is of interest here to point out that the starting-point for 

 the arrangement of the genera within the Cordulinai bv Needham 

 (1908), and within the Libellulinie by Ris in the work just 

 noticed, is the similarity of form and venation in fore- and hind- 

 wdngs, a point of view not taken in de Selys's work. 



Other articles in which some of the larger features of the 

 classification of the Odonata have been considered are those of 

 Calvert (1902) on Zygoptera, Needham and Hart (1901) on the 

 iî^schnidiE [sensu Selysii), Needham's reports (1901, 1903) on 

 the Aquatic Insects of the Adirondacks, Tilly.vrd in his Syn- 

 thetnis monograph (1910) already quoted, and Martin's .Esch- 

 nines (1911) in the Genera Inscctorum of Wytsman. 



The taxonomic study of the larvœ has also made great pro- 

 gress, and the number of species whose early stages have been dis- 

 20 



