HYMENOPTERA. — UROCERIDZ. Niles 
with those of the saw-flies ( fig. 70. 12—~19.), we are at once struck 
with the relations existing between several of their parts; the minute 
style (a) and the 2-jointed outer sheaths (6 and 6 b) are perfectly 
analogous, so that we are at once led to the opinion that the borer of 
the Urocerus is but the saw of the Tenthredo, modified ta fit it for 
its functions. ‘The Tenthredinidz ordinarily oviposit in the soft sub- 
stance of leaves, and their saws are accordingly of a delicate struc- 
ture ; but the Uroceridez deposit their eggs in sound timber, and 
have need of a far more powerful instrument. In order, therefore, 
that their instrument of oviposition should possess sufficient strength, 
it is not only horny, but the two compressed back supports of the 
saws of the Tenthredo are soldered together into a cylinder c, which, 
both as regards its situation with the spicule, and its action as a sup- 
port to them, cannot but be analogous to these supports. The two 
spiculz of the Urocerus, on the other hand, are clearly analogous, 
both in action and almost in their serrated structure, with the sawing 
parts of the two saws of the Tenthredo. Burmeister, indeed, first 
correctly describes the superior channel of the terebra as including a 
double bristle; but, as we shall see that there is a precise analogy 
between the borers of Urocerus and Ichneumon, we cannot adopt 
Burmeister’s view (Manual, p.198.), that the upper half tube (c) is 
formed of the two entire saws of the Tenthredo, and that the lower 
part of the terebra (or the two spicula) is an elongation of a small 
triangular plate which exists at the base of the saws of the Ten- 
thredo. 
With this powerful boring apparatus the females are enabled to 
deposit their eggs in timber, especially preferring the various kinds 
of firs. The larva of Urocerus Gigas has been figured by Rosel, and 
that of U. juvencus by Hartig. Iam indebted to Mr. Raddon for an 
opportunity of examining one of the latter ( fig. 72. 17.). The larvae 
are long, cylindrical, fleshy grubs, with the segments transversely 
plicate: the head (fig. 72. 18.) is small and horny, destitute of eyes, 
but furnished on each side, above the jaws, with a minute conical an- 
tenna, articulated, as it appears to me, both at the base and extremity 
( fig. 72. 19.), although represented by Hartig as exarticulate ; with 
the exception of the jaws, the parts of the mouth are small ; the upper 
lip arises from a distinct transverse clypeus ; it is transverse, with the 
anterior angles rounded off, and emarginate in the centre. ‘The man- 
_dibles are horny, quadrate, one being depressed and the other com, 
13 
