and at their proper distances, are to be drawn, and cross lines equal in number to the insects contained in the rows. The distances of these lines will be uniform, unless smaller specimens are to occupy some portion of the case, when they may be graduated to the required proportion. With the sheet ruled in this manner and placed beneath the glass, the points where the corks are to be applied are indicated by the intersection of the lines. The sheet, marked with the family of the insects for which it was used, and, with the numbers designating its divisions, may be laid aside for future use in the preparation of other cases for which it may be suitable. In a series of unbound cases in my collection, in which the glasses measure 11 x 14 inches, I have used for my Lepidoptera and laid aside the following scales, the citation of which will also serve to show the capacity of the cases: 3×8, Catocalas; 2×7 and 3×9, Sphingidæ; 4 × 11 to 4x14, Bombycidae; 5×13 to 6 × 16, Noctuidae; 8×16 and 8×20, Lycænidæ and Tortricidæ.

The unbound cases above referred to are inexpensive frames, made by myself, of quarter-inch white wood or pine, the corners mitred, glued and nailed with three-quarter inch brads, lined within with white paper (better with tin-foil), and covered without with stout manilla paper. The glasses are cut of the exact size of the frame, and, when placed in position thereon, are appressed closely to it by laying upon them, near each corner, a heavy weight (the weights used by me are four-inch granite cubes, weighing nearly seven pounds each, which are sufficient to overcome the curvature of the glass); strips of an enameled green paper cut to the width of one inch, are pasted over the edges of the glass, extending a little beyond the thickness of the frame, and brought downward over the sides of the frame. On its front, two gum-labels, indicating the insects inclosed, are placed at heights respectively of seven and twelve inches, when, if all has been neatly done, the cases present a tasteful appearance upon a shelf. When there is reason to believe that the case will need to be opened for the change or addition of specimens, it will be found convenient to employ, for the fastening of the upper left-hind side of the upper glass, paper lined with a thin muslin, to serve as a hinge when the other sides have been cut.

Should it become desirable to bind these cases, outside frames may be constructed after the plans above given, with the omission of the inside quarter-inch (the equivalent of these frames), in which these may be placed and held in position by two or three screws inserted in their sides.