_Economic Displays._--In the case of economic displays, which will include pinned specimens, alcoholic material, early states and specimens illustrating the work of the insect--also the parasitic and predaceous enemies--the horizontal arrangement can be followed, and I have found it advisable, in making such displays, to arrange them in this manner, so that any needed width for the display of particular species may be had. A good idea of the system of arrangement adopted for an economic exhibit may be obtained from the accompanying illustration (Pl. I). Every insect will require a somewhat different treatment, owing to its different habit, but the plan indicated in the illustration should, in the main, be followed. Prof. J. H. Comstock uses and recommends a sort of block system, which consists in pinning the insects and specimens showing their work, and alcoholic material, to blocks of soft wood. These are then arranged in the display cases. The advantage claimed for the system is facility in transferring and rearranging the exhibits. This method is somewhat cumbersome, and in making and handling economic exhibits I have found pinning specimens directly to the cork lining of the box, as already described, to be entirely satisfactory. A biologic exhibit should be carefully planned beforehand, and when once completed is permanent and does not require rearrangement, as is frequently necessary in a systematic collection, owing to the constant changes in classification. The only alteration necessary is a renewal of specimens which have become injured, or faded by exposure to light.