18 PROCEEDINGS OF THE NATIONAL MUSEUM. vor. 62. 
the north of the peninsula, whilst I have seen a second female of 
the same species from the Malay State of Jalor which lies within the 
boundaries of lower Siam. 
Five species have been named in the genus, but one of these names 
is probably a synonym. 
The largest species, the most gigantesque of recent Odonata, is 
T. plagiata Waterhouse, recorded from Borneo, Sumatra, and the 
Malay Peninsula. The female may have a span of over 170 mm. 
The wings have a longitudinal brown costal band; and a transverse 
band of the same color is found, in the female only, between the 
nodus and pterostigma. JT’. vittata MacLachlan appears to differ only 
in that the wings of the female are without the transverse brown 
band. Doctor Ris has pointed out that it is possible that plagiata 
may have dimorphic females, vittata in that case becomes a synonym 
of plagiata. T. brunnea MacLachlan, from the Malay Peninsula and 
Borneo, is much smaller, with a span of rather less than 140 mm. 
The wings of the female are colored much as in plagiata, but the 
sides of the thorax are uniformly brown, whilst in plagiata, the thorax 
has two pale brown bands on either side. 7. degorsi Martin, from 
Borneo, of about the same size as brunnea has a longitudinal band on 
the wings in both sexes, a very small yellow pterostigma, and the 
sides of the thorax rather greenish in hue. Lastly, waterhouser 
MacLachlan, from Borneo and Tonkin, has unbanded wings, a very 
small pterostigma with a black mark immediately below it, giving it 
rather the appearance of occupying a double row of cells; and the 
sides of the thorax each with two pale brown bands. The female is 
again of about the same size as that of brunnea. 
The specimen of brunnea that I caught was fluttering about the 
trunk of a large forest tree. The flight did not impress me as being 
particularly powerful. 
LIST OF ORIENTAL SPECIES OF THE GENUS TETRACANTHAGYNA 
1. T. brunnea MacLachlan: Malay Peninsula and Borneo. 
2. T. plagiata Waterhouse: Borneo, Sumatra, Malay Peninsula. 
3. TJ. degorsi Martin: Borneo. 
4. T. waterhousei MacLachlan: Borneo, Tonkin. 
Genus AESCHNA Fabricius. 
Unlike the other zoogeographical regions, with the sole exception 
of Notogaea, the oriental region is characterized by a dearth of species 
belonging to this genus. 
Those which do occur, leaving out of account Japanese species 
which may in part at any rate have been derived from the Pale- 
arctic area, are found in the northeast ranges of the Himalaya and in 
Assam. Further it seems to me that of the three recorded species, 
one petalura Martin, is deserving of generic distinction. Not only 
