446 Scientific Proceedings, Royal Dublin Society. 
Excluding Celithemis, Holotania, and Pachydiplax, three Sonoran 
genera which range south into Cuba or Mexico; the NzorroPicaL 
Recron has forty-two genera of Libelluline, of which as many as 
twenty-seven are to be found nowhere else. We may reckon, 
however, thirty peculiarly Neotropical genera, as three others— 
Dythemis, Lepthemis, and Macrothemis—only range north into 
Texas, Florida, or Lower California. The Chilian sub-region is 
very poor in this sub-family, which is represented there only by 
one characteristic genus (Hrythrodiplaw), and a few species of 
three wide-ranging genera. The Brazilian sub-region has thirteen 
of the peculiar genera confined to it, but of a large proportion of 
these, only one or two species each are as yet known. Six genera 
have been found in the Brazilian and West Indian sub-regions, but 
not in the Mexican, while two are apparently quite confined to the 
West Indian Islands. Studying the distribution of species, the 
nearer affinity of the Antillean dragonfly fauna to that of South, 
than to that of Central America, has been pointed out by Kolbe* 
and the present writer.? The distribution of the genera of Libel- 
lulinee give the same result, for, excepting Micrathyria and Canna- 
phila, no genus absent or nearly so in the Brazilian sub-region is 
characteristic of both Central America and the West Indies. 
There are three genera—Perithemis, Mesothemis, and Nanno- 
themis—which are divided between the Sonoran and Neotropical 
Regions, ranging northwards to Merriam’s transition zone on the 
southern borders of Canada. Including these three, but excluding 
Dythemis, Lepthemis, and Macrothemis mentioned above, the SonoRAN 
Recion possesses fourteen genera of Libellulinz, of which four—- 
Celithemis, Plathemis, Holotania, and Pachydiplax are characteristic 
or peculiar. The remaining seven genera found in the Sonoran 
Region are all wide ranging; three of them—Pantala, Trithemis, 
and Diplacodes—are distinctly tropical, and should perhaps be 
regarded as incursors in the Sonoran. 
The Hotrarcric Rueion is inhabited by eighteen genera of 
Libellulinz, but eight of these must be regarded as incursors from 
the tropical regions Oriental and Ethiopian. Indeed, the southern 
Holarctic sub-regions show a very evident overlapping of the 
northern and tropical faunas. Five genera are peculiar to the 
Holarctic Region; two of these are confined to the Manchurian 
1 Archiy fiir Naturgeschichte, liv., 1 Band., 1888, pp. 153-176. 
? Journal Inst. of Jamaica, vol. i1., 1896, pp. 259-263. 
