1889. ] MR. W. F. KIRBY ON NEW ODONATA. 297 
the black of the wings has become first blue-black, then brightly 
shot with bluish purple, and finally streaked at the base with metallic 
blue and green. Then, again, if the white of the secondaries was 
first modified into yellow and orange as in Bracca and Presos (in 
which the primaries are still black and white), one can see how the 
bands on the primaries of Milionia drucei and M. snelleni, if derived 
from such a source, may have remained orange after those of the 
secondaries had become vivid crimson. 
It has been said that colour is of no value as a guide in classifi- 
cation, but I am not at all sure that, if the natural order of its 
development were strictly looked to, it would not be of assistance in 
guiding one to a judicious arrangement of allied genera. 
EXPLANATION OF PLATE XXXI, 
Fig. 1. Bracca bajularia, p. 294. 
2. Craspedosis extenuata, p. 295. 
3. Lithopsyche antiqua, from the typical specimen, p. 294. 
4. Fore wing of Presos mariana, p. 294. 
5. Calospila leucomela, p. 295. 
6. Restoration of Lithopsyche. p. 294. 
3. Descriptions of new Genera and Species of Odonata in 
the Collection of the British Museum, chiefly from 
Africa. By W. F. Kirpy, F.E.S., Assistant in the 
Zoological Department, British Museum, Natural 
History, S. Kensington. 
[Received April 26, 1889. ] 
On looking through the collection of Odonata in the British Mu- 
seum lately, I found examples of some very interesting species which 
appear to be undescribed, and which form the subject of the present 
paper. Among these, the most important is Zatocnemis malgassica, 
a species representing in Madagascar two remarkable Eastern genera, 
Priocnoenemis and Idiocnemis, hitherto ouly known from the Philip- 
pines and New Guinea respectively. 
The following is a list of the genera and species which I propose to 
describe :— 
OponatTa. 
LIBELLULID &. 
LIBELLULINE. 
Orthetrum CAMAPENSE, NT. 8. ....2-seeesecenvesecenseens Cameroons. 
AD GUIELOTMAIUG TELIA, T. 85) wo cu ndee< chee s-scasoun=-5esese Madagascar. 
JESHNID AE, 
Gomrnine. 
Pseudogomphus (n. g.) insignis, N. 8. ....0.see eee ees Cameroons, 
JESHNINE, 
VANITL BUPIQLUS, Das etatecteace sess dececaaeqenetesseothe Chili. 
