_General Directions._--It matters little how much care and pains have been taken in the preparation and mounting of specimens, they will have little value unless accompanied by proper labels giving information as to locality and date of collection, name of collector, and a label or number referring to notebooks, if any biological or other facts concerning them have been ascertained. There should be pinned to the specimen labels referring to, or giving all the information obtainable or of interest concerning it. A somewhat different style of label will be found necessary in the case of the two forms of collections described in the foregoing pages, namely, the biological or economic collection, and the systematic collection. For the former, numbers may be attached to the specimens which will refer to the notes relating to the specimen or species. For the latter, in most cases, all necessary information may be recorded and made available by written or printed labels attached directly to the specimens. In most cases, however, I find a combination of these two systems convenient and desirable. The numbering system is very simple, and is the one which I have followed in all the species for which I have biological or other notes. It consists in giving each species, as it comes under observation, a serial number which refers to a record in a notebook. With this number may be combined, if convenient, the date of rearing or collection of the specimen, and also the locality and food-plant if known. The vast number of species represented in a systematic collection renders the numbering system entirely out of place and inadequate, and the labeling system alone is generally available. If it becomes necessary in the systematic collection to refer to food-plants or life-history or any other fact of interest, the numbering system should be used, and I recommend that the numbers be written in red ink on the labels, to distinguish at a glance the numbers referring to biological notes from other numbers that will occur in the collection.