PLUME-MOTHS OF CEYLON. 
3 
Identification. 
One of the great difficulties of all local workers at zoology in the 
tropics lies in the identification of their specimens. “ Si nomina 
nescis, perit et cognitio rerum,” and nowhere is this truer than in 
entomology. Considerations of space have prevented my giving a 
detailed description of all the species, but the tables will facilitate 
determination, which may then be confirmed by reference to the 
descriptions and figures cited under each species. 
There should be little difficulty in identification by means of the 
analytical keys to the genera and species, but a few words of expla¬ 
nation may be advisable. Each key is dichotomous throughout, 
that is to say, each heading is subdivided into two until the final 
results are reached. Each head is numbered consecutively, and 
each subdivision of a head is made to refer either to a final result or 
to a following head. There are two stages in the identification of 
any species, the finding first of its genus and secondly of its specific 
name. 
To take an actual example. Firstly, we have to note whether 
the wings are fissured or not; we find they are fissured, and are 
referred to the number 3 on the right of the page. Now, turning to 
the number 3 lower down on the left of the page, we see that the 
fore wings have two lobes and are referred to the number 4, which 
we follow down in the same way. The cilia contain distinct scale - 
tufts, which brings us to number 5. The dorsal cilia of third 
segment of the hind wing contain a distinct scale-tuft, which refers 
us to number 9. The second segment of the fore wing is distinctly 
broad, so that the specimen must fall under number 10 and, as 
the segments of the hind wing are differently shaped, it must be a 
Platyptilia . 
The second stage is to find the specific name. We turn to the 
Synopsis of the Species of Platyptilia and note that our specimen 
has the abdomen shorter than the dorsum of the fore wing, its 
pectus is not yellow, and the large scale-tooth on dorsum of third 
segment of the hind wing touches the apex, so that the moth must be 
P. pusillidactyla, an identification whose accuracy is strengthened 
on turning to that species by the fact that we bred it from a boxful 
of flower and seed heads picked off a Lantana bush. 
In drawing up the key to the genera some difficulties have pre¬ 
sented themselves, due to the fact that I have endeavoured to make 
use only of characters easily made out by means of a simple lens at 
most, without the aid of the microscopic manipulation'necessary 
to determine details of neuration, &c. ; however, it is hoped that 
local collectors will find the table quite workable. Should examin¬ 
ation of the neuration be necessary the following method may be 
adopted : take a glass slide and smear on its centre a thin layer of 
clove oil with a fine brush, remove the wings and place them in 
