124 SOCIAL HABITATIONS. 
It is nearly flat, “abruptly truncated” according to 
scientific language, and throws out several projections 
like horns or spines. The reader will remember that the 
ink-gall also possesses short and sharp projections, but 
they start from all parts of the surface, whereas in the 
present species they belong wholly to the flattened end. 
Their number is variable, so that the end of the gall 
is sometimes triangular and sometimes squared, besides 
assuming other forms according to the number of projec- 
tions. This remarkable form has earned for the insect 
the name of polycera, this term being derived from two 
Greek words which signify ‘‘many-horned.” The insect 
which forms this curious gall is about half as large as 
Cynips Kollart. 
The last example which is represented in the illustra- 
tion is also found in Germany upon the oak, and is made 
by an insect which is called Cynips Hungarica. 
This gall is represented of the natural size, whereas 
all the others are much diminished, in order to be in- 
serted in so limited a space. It is a very remarkable 
object, and cannot be mistaken for any other species. 
Its surface is traversed by a variable number of irregular 
ridges, which all radiate from the stem, and so pass 
longitudinally over the gall. The whole of the ridges 
are rough and sharp-edged, but at intervals they shoot 
out into hard-pointed horns, much like those which arm 
the preceding species. Indeed, the whole substance of 
the gall is remarkable for its hard texture, for when cut 
with a knife it offers as stubborn a resistance as if it 
were seasoned oak or elm. a 
That a hymenopterous insect should be able to bore 
its way through so hard a substance, and to make a 
tunnel barely wide enough for the passage of its body, 
