288 
That Förster has been unable to see the anellus, he must 
be excused for, as it is often difficult enough now a days 
with our modern good microscopes to observe the various 
joints of the antenna of these very small Hymenoptera — 
so that we can easily imagin how much more difficult it 
has been in Försters time. 
However, when looking at the figures of the wings 
(Förster 1851 Plate I fig. 9 a--b—c, reproduced by Wolff) 
and further reading (Wolff p.562).: „Der Bohrer soll nach 
Förster etwas aufwärtsgekrümmt sein. Das Männchen 
hat einen an der Spitze des Hinterleibes lang vorgestreck- 
ten Penis, dessen Länge wenigstens 4 von der Länge des 
Hinterleibes betragt“, it is almost impossible not to be able 
to judge the appearance of Centrobia, of course when 
having a specimen of-the genus to examin. The wings 
with the long ramus marginalis, and all the hairs in re- 
gular rows are so characteristic, as none of the European 
species known at present having such regular hairs on the 
wings. I must however critisize Förster when he finally 
states that it is his opinion that Centrobia on account of 
its long ovipositor is a parasite on the eggs — or larvæ — 
of bark-beetles, as although the species has a relatively 
long ovipositor, but exceedingly weak when considering 
the bark of trees, is in my opinion quite unable to pene- 
trate such hard material as bark. I have also found all 
my specimens where there were no bark-beetles in the 
neighbourhood, and in reality why should Centrobia be 
provided with a long ovipositor for barkbeetles, it would 
be decidedly easier for it to make its way in the galle- 
ries. The chief characters of the genus are as follows: — 
Antenne eight jointed: scape, pedicellus, 1 anellus, 2 
funiculus, and three-jointed clavus. Head triangulate, 
eyes round, large, red, ocelli placed close together, red. 
Antenne placed near mouth, below eyes. Mandibles with 
three teeth. Head and thorax together as long as abdomen. 
Parapsid furrows distinct. Abdomen long narrow cy- 
lindrical. 
Ee 
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