stridulation in ants. — 205 
structure are greatly in need of elucidation. I have great 
doubts whether it ought to be placed in the Ponerides. 
Poneripes ?. — Myrmecia, sp.?. The second post- 
nodular segment has a broad neck, which is perfectly 
cylindrical; this neck is completely different in sculp- 
ture from the rest of the segment (and also usually in 
colour, resembling in this latter respect the previous 
segment by which it is covered). The sculpture is a 
beautifully developed system of transverse lines; they 
are everywhere the same on all parts of the neck, except 
that on the ventral surface they are a little coarser and 
less regular. The hind margin of the post-nodular 
segment has so minute a scraping edge that it can only 
be satisfactorily detected by separating the segment. 
I have examined several species of this most inte- 
resting genus of ants—the “‘bull-dog ants” of Australia; 
they are all similar, with some slight distinctions in the 
sculpture. The condition is not that of a differentiated 
stridulating organ, as the lines are not perfectly regular, 
and cover the whole surface. Nevertheless, I think it 
probable that the parts may act as a sound-producing 
organ, by, after the manner of the Ponerides, retracting 
and extending the segment; the very fine minute 
scraping edge striking against some of the lines here 
and there notwithstanding their slight irregularities. 
PoneRIDES. — Amblyopone obscura (worker). The re- 
tractile portion of the post-nodular second segment is 
very sharply defined, and is covered with a system of 
symmetrical sculpture, which, though it extends chiefly 
in the transverse direction, does not form straight lines. 
The scraper on the hind margin of the preceding seg- 
ment exists, and its hind margin possesses apparently 
some excessively minute crenulations. 
Although there is no definite stridulating organ in this 
insect, I should think the parts act as if there were one, 
and with the result of producing a sound of a much less 
perfect character. The female is like the worker in 
these respects. This is an insect of extreme insect. 
During an examination I have lately made of the external 
skeleton in ants, I came to the conclusion that this was 
the most primitive of the existing ants known to me, and 
also that it should form a separate subfamily on account 
of the imperfect differentiation of the node. On com- 
municating my view to Prof. Forel, he informs me that 
