with the basal joint much dilated. Fam. Andrenidæ, Apidæ.
In illustrating this order more in detail, we shall first select a characteristic example from the family of the Tenthredinidæ.[1]
Fam. Tenthredinidæ.
This extensive family may be known by having the abdomen sessile, or united by its whole breadth to the hinder part of the thorax, in such a manner, that it possesses but little power of separate movement. The maxillary palpi are always six-jointed; the labial four-jointed; labium trifid; wings ample, and provided with many complete cells; females with an ovipositor.
It is from the use and appearance of the instrument just named that these insects are called saw-flies. It is placed at the extremity of the abdomen of the female on the under side, and is so constructed, that it combines the properties of a saw and auger. It consists of two plates of the same form and size as two external valves, which serve as a sheath to them, and enclose a short triangular
- ↑ We purposely exclude from these illustrations the most interesting of all the hymenopterous families, the Apidæ, as their history has already been given in a way commensurate with its importance, in a separate volume. The details there afforded of this characteristic group are so ample, as to preclude the necessity of entering at such length into the generalities of the order in the above sketch as it would otherwise have been necessary to do.
