This is a small insect—that is it is smaller than some of the dragon flies, to which order—Odonata—it belongs. It is of more gentle habits and not so swift of wing as the dragon fly. It was the French writers who gave it the name it bears, while some English authorities placed it along with the dragons. Howard says they are seldom found far from the stream or pond where they are born, yet I have two or three varieties that I caught on the prairie some miles from any water. Their wings are not held horizontally, but are folded parallel with their bodies. This facilitates the backing down the stem of a plant or reed when the female wishes to deposit her eggs below the surface of the water, which is usually the place for incubation. The wings are gauze like, some nearly black, others with a beautiful metallic luster. They are not so savage as the dragons, although one I took last summer held on to the threads of the net until it nearly severed them, and bit at my fingers in a most savage manner. Alvin M. Hendee. FELDSPAR. Feldspar is the family name of several minerals closely related and indeed grading into each other, but distinguished by mineralogists by separate specific terms. These minerals are all silicates of aluminum, with some alkali or alkali earth, having a hardness of about 6 in the scale in which quartz is 7 and a specific gravity varying from 2.5 to 2.7. They are fusible with difficulty before the blowpipe, crystallize in the monoclinic or triclinic system and cleave in two well-marked directions nearly or quite at right angles to each other. It is this latter property, probably, which led to the grouping of these minerals as spar, since this term is applied in common language to any minerals which break with bright crystalline surfaces. Thus calc spar is a common name for calcite, heavy spar for barite, needle spar for aragonite, and so on. The term field spar, of which Feldspar is probably a corruption, was perhaps given the minerals of this group because of their widespread occurrence. The English spelling of the word is Felspar. The Feldspars form an essential part of nearly all eruptive rocks and by their decomposition produce clays and other soils which may harden into great areas of sedimentary rocks. They are thus of great geological importance and interest. Usually the white crystals to be seen in an eruptive rock in contrast to the dark green or black of the pyroxene or hornblende, or the glassy, nearly colorless quartz, are Feldspar. The Feldspar may, however, contain more or less iron and then take on a flesh color or become even darker. Feldspar crystals can best be recognized by their prominent cleavage, which appears as numerous bright flat surfaces extending in any given crystal in the same direction. The crystals, while they may be of so minute dimensions as to be visible only with the