[O] The following three genera are not sufficiently well defined to place in this synopsis. In color and structural characters they are closely related to Cynomyia from which they may be distinguished as follows. Catapicephala Macq., represented by the species C. splendens from Java, has the setæ on the facial ridges rising to the base of the antennæ and has median marginal macrochætæ on the abdominal segments two to four: Blepharicnema Macq., represented by B. splendens from Venezuela has bare genæ, oral setæ not ascending; tibiæ villose; claws short in both sexes; Sarconesia Bigot with the species S. chlorogaster from Chile, setose genæ; legs slender, not villose; claws of the male elongate.
[P] Plinthomyia Rdi. and Hemigymnochæta Corti are related to Ochromyia, though too briefly described to place in the key.
APPENDIX
HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS
The following directions for fumigating with hydrocyanic acid gas are taken from Professor Herrick's circular published by the Cornell Reading Course:
Hydrocyanic acid gas has been used successfully against household insects and will probably be used more and more in the future. It is particularly effective against bed-bugs, and cockroaches, but because it is such a deadly poison it must be used very carefully.
The gas is generated from the salt potassium cyanid, by treating it with sulfuric acid diluted with water. Potassium cyanid is a most poisonous substance and the gas emanating from it is also deadly to most, if not all, forms of animal life. The greatest care must always be exercised in fumigating houses or rooms in buildings that are occupied. Before fumigation a house should be vacated. It is not necessary to move furniture or belongings except brass or nickel objects, which may be somewhat tarnished, and butter, milk, and other larder supplies that are likely to absorb gas. If the nickel and brass fixtures or objects are carefully covered with blankets they will usually be sufficiently protected.
There may be danger in fumigating one house in a solid row of houses if there is a crack in the walls through which the gas may find its way. It also follows that the fumigation of one room in a house may endanger the occupants of an adjoining room if the walls between the two rooms are not perfectly tight. It is necessary to keep all these points in mind and to do the work deliberately and thoughtfully. The writer has fumigated a large college dormitory of 253 rooms, once a year for several years, without the slightest accident of any kind. In order to fumigate this building about 340 pounds of cyanid and the same amount of sulfuric acid were used each time. In addition to this, the writer has fumigated single rooms and smaller houses with the gas. In one instance the generating jars were too small; the liquid boiled over and injured the floors and the rugs. Such an accident should be avoided by the use of large jars and by placing old rugs or a quantity of newspapers beneath the jars.