stridulation in ants. 203 
band, in other places the lines of the stridulating band 
project into those of the neighbouring sculpture. These 
conditions show conclusively that the stridulating band 
is formed out of the general sculpture of the segment by 
this becoming more regular, finer, and denser. In the 
two individuals examined there is considerable difference 
in the outlines of the band, and in one the strie and 
sculpture seem to be finer than in the other. The hind 
margin of the preceding segment ig delicate, and is 
slightly crenulated so as to be irregular in outline ; but 
the crenulations are absent from the part which lies 
over the file of straight lines, so as to make this part 
perfectly regular, and to correspond exactly with the file. 
PI EX. figsa 1&2. 
PonsripEs.— Paltothyreus commutatus, Rog. Amazons. 
In the middle of the dorsum of the retracted part of the 
third abdominal segment there is a longitudinal band of 
fine, perfectly parallel, lines; these lines extend over 
the greater part of the length of the retractile portion of 
the segment; the sculpture of the adjacent parts eon- 
sists of coarser, more distant, and less regular lines, 
which are broken up into comparatively short pieces. 
PonERIDES. — Ponera contracta (worker). England. 
The sculpture of the retracted portion of the segment is 
in this species remarkably coarse and distant, while in 
the middle there is a band of extremely fine lines, so 
different from the rest of the sculpture that it would not 
be believed to be a modification thereof. In this species 
the band is more “differentiated” than in* any other 
Ponerid I have observed; by this I mean that there is a 
greater and more abruptly limited difference between it 
and the adjacent parts. Fig. 3. 
PonERIDES. — Ponera ? sp. (worker). Hobart. Very 
rough sculpture: worker. The apical part of the retrac- 
tile portion of the segment consists of lines of deep 
rather coarse sculpture, which are but very little broken 
up or irregular; nearer to the base the segment is very 
much more densely and finely striate ; in the middle of 
the dorsal region these strie leave a broad space, which 
appear highly polished and smooth, but which, on exami- 
nation with a high power, can be seen to be very densely 
covered with perfectly regular, densely-packed, lines. 
Independently of the extremely fine striation this 
species is remarkably different from Dinoponera, on 
P2 
