Vol. xxx] ENTOMOLOGICAL 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 Neuroptera of North America 
(1861)—¢ 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 
(1905), made the hind prothoracic lobe the primary character, closely 
followed by venation. , 
Dr. Ris has placed the genera of the Libellulinae in ten groups,7 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 ausschliesslich auf die 
Fliigeladerung aufgebaut; von andern Merkmalen ist nur noch der Bau 
des Prothorax in grésserm 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. 
7 To three of these groups Dr. Ris gives names: VIII. Die Trithemis- 
Gruppe, IX. Die Macrothemis-Gruppe, X. Die Tramea-Gruppe. Dr. 
Tillyard (Biology of Dragonflies, 1917, pp. 269-273) has a synopsis of 
these groups, which he calls tribes; he has, however, united Dr. Ris’s 
groups IV and V into one tribe and VIII and IX into one tribe, thus 
8 tribes in all; to these tribes he gives names. 
