9 
new Genus and Specics of Odonata. 231 
hardly at all curved or waved, and separated fiom Rs at the 
widest interval by three rows of cel/s. Mz reaching the hind 
margin of the wing at about the level of the bifurcation of Rs. 
M/, not bent away abruptly from M, beyond the level of the 
nudus, but curving away trom it gently, so as to admit two 
rows of cells from the level of the proximal end of R. suppl. 
to the hind margin of the wing. At least seven cross-veins 
in the supertriangle. Subtriangle traversed by a single cress- 
vein. Five other cubito-anal cross-veins, amongst which 
the anal crossing is not discernible. Triangle very long, 
narrow, its base comparatively broad and bowed towards the 
interior of the enclosure, its long axis directed outwards and 
not at all forwards, containing seven cells, two of which ~ 
surmount a single large cell at the base. rig. suppl. long 
and well developed, gently curved, its proximal end resting 
upon the triangle only a very little below the outer corner, 
its distal end reaching about as far as the proximal end of 
M. suppl., from which it is separated by one row of cells. 
AM. suppl. with a slight double curve; beginning as a well- 
defined vein soon after the level of the proximal end of the 
bridge ; separated from My, at first by two rows of cells, 
under the nodus by three rows, and towards the margin of the 
wing by two rows of small cells. Space between Cu, and 
Cu, moderately dilated at the base, and with a single row of 
cells. Cu, reaching the hind margin of the wing a little 
beyond the level of the nodus. Cu, separating quite near to 
the lower corner of the triangle, and continuing as a distinctly 
marked vein about as faras the level of thenodus. The cells 
between this vein and the hind margin of the wing numerous, 
and arranged for the most part in oblique rows, thus giving 
to Cu, an appearance of branching. The usual two rows of 
cells between the anal vein and the hind margin of the 
wing; twelve cells-in the upper row. ‘The membranule not 
preserved. 
Type of the genus and species the above-mentioned fossil 
and its counterpart in the British Museum (Natural History), 
Geol. Dept., reg. no. I. 2595. 
There are several other fossil dragonflies with which 
Trieschna gossi may be usefully compared. The oldest of 
these appears to carry the history of the Adschnine well back 
into Mesozoic times, for a figure of Morbeschna muensteri, 
Germar, published by Prof. James G. Needham (Bull. Amer. 
Mus. Nat. Hist. xxii. p. 142, 1907), shows a venation com- 
parable with that of the North-American Zeschnine Gomph- 
eschna furcillata, Say, and evidently coming within the same 
subfamily. ‘The history of this fossil is not given, but the 
