some Notes on Oriental Dragonflies: 
the Genus Macromia. 
By F. FP. LAmaw, M.A, (CANTAB.) 
The following account is the result of a study of examples of 
some twelve of the Oriental species of the genus, that I am for- 
tunate enough to have before me, apparently a greater number of 
species than was available to Martin in preparing the Selysian 
Catalogue of the CorDULIINAE. Species of the genus are rather 
scarce in collections, and being at first sight often somewhat uni- 
form in colouring and build, their discrimination is a little diffieult. 
Dr. Ris, who has the gift of illuminating the dark places of 
systematic Odonatology, has not very long ago defined a small 
group of species belonging to the genus (Suppl. Entomol. 
pp. 65-70, 1916) using characters that are easily determined 
and of due importance. He has thereby paved the way for a 
further grouping of the Oriental, and especially of the Malayan 
species, such as I attempt here. 
Employing characters similar to those made use of by Dr. Ris. 
I arrange the Malayan species in groups, one of which is of course 
the group already defined by Dr. Ris. This grouping, unfor- 
tunately dependant in part on sexual characters, is I think 
tolerably natural, and should, with the aid of figures given, 
facilitate the determination of species. It is impossible to provide 
a satisfactory dichotomic table or key. I therefore give definitions. 
of the groups, and under the heading of each group is added a short 
but I hope sufficient account of each of the species referred to that 
group. Fuller notes on the new species and remarks on some of 
the others, with text-figures, are appended. 
The characters relied on for the defining of the three groups. 
of species I note below have already been employed by Dr. Ris in 
his paper, and suggested by Martin in the Monograph as useful. 
These characters are: firstly the colouring of the post-clypeus, 
which may be yellow, or may agree with that of the rest of the 
front of the head in bei ig reddish brown or dark-brown. Secondly 
the presence or absence of a humeral stripe on the synthorax; note 
that a lateral oblique stripe of yellow is present in all Oriental 
species of the genus. Thirdly the presence or absence of a flat- 
tened, pointed, triangular process on the dorsum of the tenth 
segment of the abdomen of the male. 
Specific characters are: the colour pattern of the abdominal 
segments, the occurrence of metallic lustre on some of the more 
basal of those segments, the colouring of the costal nerve, (? 
occasionally variable), the number of ante- and post-nodal nerves. 
Jour. Straits Branch 
