468 Scientific Proceedings, Loyal Dublin Society. 
genera. These groups, it will be remembered, are better repre- 
sented in Tertiary than in Secondary rocks, and are clearly the 
most vigorous and flourishing branches of the order. The 
Adschnine, a group which seems to have passed its zenith, and 
the Corduliine show a larger proportion of forms peculiar to 
various regions. Lastly, in the Gomphine and the Agrionina, 
with an excessively large percentage of genera of restricted range, 
we see the evidence of their geographical distribution strongly 
confirming the opinion of students of their structure, that they 
are the most primitive of the dragonfly sub-families. In several 
large genera, the American species largely outnumber those in- 
habiting the Old World. Such distribution appears to show an 
approach to that of those ancient groups which have become 
altogether extinct in the eastern hemisphere, while they still 
flourish in the great western continent. 
Having given in the tables the distribution of the genera, so far 
as I have been able to ascertain the facts, it seems unnecessary to 
repeat the same information in maps. I have, therefore, thought 
it sufficient to give a single map which indicates generally the 
main features of dragonfly distribution over the earth’s surface, 
showing the extent and overlapping of faunas rather than the — 
boundaries of regions and sub-regions which will be sufficiently 
familiar to readers of the present Paper. 
