108 JOURNAL, BOMBAY NATURAL HIST, SOCIETY, Vol. XXVIII. 
into two or more cells and defined by a straight nervure which leaves the sub- 
costal nervure and forms the acute point of the triangle by meeting the anal 
border near the anal angle (or tornus). In the group Anaa the similarity 
between the two sexes is very marked, the anal triangle disappearing in both 
completely. 
Oreillets more or less developed or in the group Anaz, entirely absent. The 
connection between these organs and the excavation of the hindwings has al- 
ready been commented on in dealing with Hemicordulia asiatica. 
Lhe basal space (for which I propose the new name “ arcular space ”’ as it 
is limited outwardly by the arc) is either entire or traversed by several ner- 
vures. The 4th nervure (nodal sector) either curved uniformly or making an 
abrupt curve towards the costa beneath the stigma; the 5th nervure (Rs or 
subnodal sector) either bifurcated or not. at or before the inner end of the 
stigma. 
Q The terminal border of the 10th abdominal segment beneath (known 
as the ‘“‘dentigerous plate”) most generally rounded and most often den- 
ticulate, but in Gynacantha, Gynacantheschna and Pericschna it is prolonged 
into a long, bifurcated fork. 
Hat.—Cosmopolitan. 
It is impossible to give an entirely satisfactory key for this subfamily owing 
to the paucity of our knowledge of several forms of which only one or the other 
Sex is at present known. This applies especially to the imperfectly Inown 
genera Cali—and Cephaleschna. 
Dr. Laidlaw in the Records of the Indian Museum has pointed out the errors 
which have crept into the nomenclature of the species of these two genera and 
these may be usefully recapitulated here. 
The genus Calieschna was founded by Selys in 1883 Aschna microstigma, 
Schneider, being the type. The rounded, subdenticulate, dentigerous plate 
which is a characteristic of the female of this species was unknown to Selys 
when he founded the related genus Cephaleschna from C. orbifrons in 1885 and 
he gave the same character as of generic value to this genus. 
Noticing that Selys had overlooked the character of the dentigerous plate 
in Calieschna microstigma, Martin, in 1909, made the error of suppressing the 
genus Cephalechna and of placing C. orbifrons in the genus Calieschna without 
taking into account the diversity of the two species in other respects. A dis- 
tinguishing feature is the remarkable development of the frons in Cephale- 
schna orbifrons as compared with the normal development found in Caliceschna 
microstigma. 
Karsch in 1891 taking the development of the frons as the most important 
feature described Cephaleschna sikkima. In this species the dentigerous plate 
of the female is forked very much the same as is found in species belonging to 
the genus Gynacantha so that it clearly cannot be placed in the genus Cephal- 
eschna and for a similar reason it falls outside the range of Calieschna. 
Thus it is seen that Cephaleschna must be retained and a new genus must 
be erected to contain Karsch’s species, and others resembling it. 
The three genera may be briefly defined as follows :— 
1. Caliwschna with the dentigerous plate of the female rounded and sub- 
denticulate and the frons of normal development. 
Type—C. microstigma, Schneid. 
2. Cephaleschna with the dentigerous plate of the female rounded and 
subdenticulate and the frons remarkably developed.— 
Type—C. orbifrons, Selys. 
3. Gynacantnesohna gen. nov. with the dentigerous plate of the female 
forked and the frons remarkably developed. 
Type. —C. sikkima. Karsch. 
