No 
No 
Records of the Indian Museum. [VoL Sau: 
b. Thorax blue with a black line on either 
side of carina. Superior anal append- 
age falcate in profile with a large in- 
ternal two-pointed tooth _... ... P. bidentatum, Morton. 
ii. Segments 8-9 blue,! 10 black dorsally. 
c. Dorsum of thorax with three narrow 
black stripes. Superior anal append- 
ages as long as segment 10; marked 
with white internally P. microcephalum (Ramb.). 
d. Dorsum of thorax with three broad black 
bands. Superior anal appendages only 
half as long as segment Io ... P. australasiae, Selys. 
iii. Segments 8, 9, 10 blue.! : 
e. Upper lip and head largely blue, anal 
border of segment 10 moderately exca- 
vate, spines on border very small. Su- 
perior anal appendages unequally bifur- 
cate in profile, black above, whitish be- 
low; lower pair truncate, much shorter 
than upper pair P. decorum (Ramb.). 
f. Upper lip and head largely orange- brown : 
anal border of segment 10 deeply exca- 
vate, beset with strong black spines. 
Upper anal appendages. not bifurcate in 
profile. J.ower pair nearly as_ long, 
pointed ee oe .. P. rubriceps, Selys. 
B. Abdominal segments all blue except 9, 
which is black above a ... P. agureum, Selys. 
To supply any key for discrimination between the females of 
these species is a much more difficult matter. 
In the first place the Museum material acleie= female speci- 
mens of two species only, wz. of P. microcephalum in some abun- 
dance, and a solitary female of P. decorum. Secondly the females 
of P. hypermelas and of P. bidentatum are quite unknown and 
thirdly it is evident that characters which can be used for pur- 
poses of identification are much harder to find than in the case of 
the males. 
In a general way the female of P. azureum can be contrasted 
with those of the other species that have been described by the 
absence in it of any black markings on the abdomen, which ac- 
cording to Selys is bluish (bleudtre) in colour, paler beneath. 
The remaining species of which any account is available all 
have black markings on the abdomen on segments I-9. 
P. microcephalum has the post-ocular spots of a fairly bright 
blue colour with blue on the thorax. P.decorum, which is a rather 
larger insect, has green post-ocular spots and the ground colour of 
the thorax is distinctly green. That of P. australasiae is also 
larger than P. microcephalum and according to Selys the black 
marks on segments 8 and g are more extensive than in the smaller 
species. 
Lastly P. rubriceps is described as having the upper lip of an 
orange colour, the rest of the head yellowish with blue post-ocu- 
lar spots, the thorax orange yellow. 

1 The sutures of these segments are ringed with black. 
