228 [March, 
tarsi appear to be 2- or 3-joiiited according to the species, as in the 
imago ; I certainly possess larvae or pupae with both 2- and 3-jointed 
tarsi. The idea expressed by Westwood in his " Introduction," vol. ii., 
p. 19, that there is probably a sexual variation in the neuration, appears 
to have been based on an insufficient knowledge of the specific charac- 
ters. I possess both sexes of most of the species, and nowhere do I 
find sexual variation in this respect. As in all other Neuroptera, the 
neuration is occasionally liable to individual aberration, but only in an 
unimportant degree. This aberration generally consists in the veins of 
one wing of an individual belonging to a particular group or genus, 
showing a tendency to assume partially the characters of other groups ; a 
fact which to the philosophical entomologist is pregnant with signifi- 
cance. The occasional occurrence of micropterous forms is interesting. 
I have observed these forms in at least five species, and they probably 
occur in all. It is also possible that some individuals never acquire 
wings, though otherwise fully developed; a supposition which the 
evident analogy with Termes renders additionally worthy of obser- 
vation.* 
In all their states they probably feed on dry vegetable matters and 
lichens. They are universally common, more or less in societies, on 
tree-trunks, and palings, and amongst the herbage of trees, especially 
firs, larches, and yews ; and some species in houses and warehouses. I 
believe that both sexes possess the power of spinning web, not distin- 
guishable from that of spiders. If a number of living specimens be 
enclosed in a pill-box, it will be found that, at the end of a few hours, 
the interior is traversed in all directions by numerous lines of web. 
They are exceedingly active and diflBcult of capture. 
The British genera may be tabulated as under — 
A. Tarsi 2-jointed. 
a. Pterostigma free. 
* Discoidal cell closed, quadrate ; four complete cellules on 
apical half of the posterior margin Fsocus, 
** Discoidal cell incomplete, open. 
f Three complete marginal cellules ; the last (counting 
from the apex) elliptical and free Ccecilius. 
ft Two complete marginal cellules ; the last altogether 
absent Peripsocus. 
* In the micropterous forms (which are probably always females) the neuralion differs slightly 
from the normal arrangement. Yet the deviation is usually less than would be expected from the 
ahiidgcment of the wings, and seems to consist in a shortening of the apical cellules. A micropterous 
example of Psocus nebulosus has an altosether normal neuration, excepting that the pterostigma is 
much abbreviated ; a similar form of Stenopsoc^is cruiiatus presents an irregular formation of the 
cellules on the posterior margin. The forms noticed in the remarks on Lac/iesis, and which I imagine 
to be this state of C/ecUius pedlculariiis, sliew no trace of the posterior marginal cellules. 
I 
