Vol. XXXl] K \TOMOLOGICAL NEWS 27 



references, of the 120 genera and 556 species recognized (pp. 1247-1258) 

 and an alphabetical index of the taxonomic names (pp. 1259-1278). 



It is distinctly astonishing to find that as far back as 1893 the known 

 genera and species of this subfamily were already reckoned at 104 and 

 525, respectively.* Dr. Ris has admitted many species and genera de- 

 scribed since that time, but he has also relegated many of the earlier names 

 to the synonymy or to the rank of subspecies, for which latter he has 

 employed trinomials. 



It is of interest to note the different bases upon which successive writers 

 have founded their classifications of the subfamily Libellulinae, which, 

 even in Burmeister's Handbuch of 1839, was represented by the single 

 genus Libellula. Newman, indeed, in 1833, proposed a subdivision into 

 genera differing in the shape of the abdomen. Rambur, in 1842, dis- 

 regarding these, used a venational character for his first dichotomy of 

 the Libellulides, followed in the next four by differentials drawn from the 

 abdomen and the eyes; the four genera still remaining were then dis- 

 tinguished by three venational, one vulvar and one thoracic character. 

 The classification of the Libellulines of Europe into two genera by de 

 Selys and Hagen, in 1850, is primarily venational, while the 12 genera 

 employed by Hagen in his Synopsis of the Neuropiera of North A merica 

 (1861) 9 of them new were largely founded on characters drawn from 

 the eyes, the posterior lobe of the prothorax, the abdomen, the legs and 

 the external genitalia and only to a slight degree from the wings. Brauer 

 (1868), dealing with the world fauna, raised the number of genera to 40 

 and, although making an increased use of the venation, relied to a greater 

 extent on the other Hagenian differentials. The diagnoses of the 88 

 genera recognized by Kirby (1889) are predominantly venational, much 

 more so than his Table of Genera, and Karsch (1890) emphasized the 

 same feature, while the reviewer, in the Biologia Centrali- Americana 

 ( I 95)> made the hind prothoracic lobe the primary character, closely 

 followed by venation. 



Dr. Ris has placed the genera of the Libellulinae in ten groups,! desig- 

 nated by numbers and based chiefly on the arrangement of the wing- 

 veins, although other features are by no means disregarded. He expressly 

 says: "Die folgende Gattungs-tabelle ist fast ausschlicsslich auf die 

 Fliigeladerung aufgcbaut; von andern Merkmalen ist nur noch der Ban 

 des Prothorax in grosserm Umfange herangezogen." It is in the resem- 

 blances of the venation of such a Libelluline as Hypothemis to that of the 



* Trans. Amer. Ent. Soc. XX, p. 207. 



t To three of these groups Dr. Ris gives names: VIII. Die Tritlicmix- 

 C.ruppe, IX. Die Macrothemis-Gruppe, X. Die Tninii-(',n\\>\H-. Dr. 

 Tillynrd (Biology of Di'n^oi/Jlics, 1917, pp. 269-273) has a synopsis <>f 

 ilicM' groups, which he calls tribes; he has, however, united Dr. Ki-'- 

 ;,;.ionps IV and Y into one tribe and YIN and IX into one tribe, thii- 

 N t libes in all; to these tribes lie gives names. 



