FIREFLY 213 are suddenly liberated by the diminution of pressure. It has been found that when this stream is projected upon a fire it possesses ex- traordinary extinguishing powers. A pair of large extinguishers may be mounted upon a carriage drawn by horses. This, known as the Babcock self-acting fire engine, is shown in fig. 3. These cylinders are capable of holding about 75 gallons each, and of sustaining an internal pressure of 400 Ibs. per square inch. Many are in use in the United States, and are found to render efficient service in extinguish- ing fires before they have spread to much ex- tent, and even then they may be used with ad- vantage as aids to the steam engine, or alone. FIREFLY, the popular name of many serri- corn beetles, belonging to the families elate- ridm and lampyridce, and to the old genera elater and lampyris of Linnaeus ; the luminous species of the former belong to the new world, those of the latter to both hemispheres ; these insects are also called fire beetles. The elaters have a firm and solid body, of an oval form ; the middle portion of the sternum between the first pair of legs is prolonged into a short spine usually concealed in a cavity behind it; the antennas in the males are simply serrated. They are called spring beetles from the faculty possessed by them of throwing themselves up- ward with a spring by means of the spine ; as they live on plants, when they drop to the ground they often fall upon the back, whose great convexity and the shortness of the legs Erevent them from turning over; the spine aving been unsheathed by bending the head and thorax backward, it is made to strike with such force against the sheath by the sudden straightening of the body, that it projects the insect into the air, and gives it the chance of coming down on the feet ; if unsuccessful, other attempts are made until the object is attained. Fireflies of this tribe are numerous in tropical America, including the West Indies. One of the largest and most brilliant is the night- shining elater, or lightning spring beetle, the cucujo of the West Indies (pyrophorus noctilu- cus, Linn.) ; this is more than an inch long, of a dark color, and gives a strong light from two oval tubercles on the dorsal surface of the Cucujo (Pyrophorus noctilucus). thorax, and from the under surface of the seg- ments of the body. Specimens are frequently brought alive to the United States, where they may be kept for some time if fed on sugar cane ; the grub is said to be very injurious to the su- gar cane by devouring the roots ; one of these was once transported to Paris, and escaping into the streets, after assuming its perfect state, very much astonished the inhabitants of that city. This insect is common in summer, both in the lowlands and at moderate elevations; according to Mr. Gosse, the thoracic light is visible even in broad daylight; when undis- turbed, these spots are dull white, but they gradually become bright when touched, the brilliancy beginning at the centre and extend- ing until the whole tubercle shines with a rich yellowish green. The light is so intense that it will cast a shadow of any object on the op- posite wall in a dark room ; the under side of the thorax seems as if it were red-hot, particu- larly beneath the tubercles ; when left to it- self, the insect becomes quiet, and the light fades to a mere speck. The insect when held in the hand shows only a green light, but when flying free it diffuses a rich ruddy glow from the ven- tral surface ; it may show the green light at any time, but the red light only when flying ; the former is seldom shown during flight, but in rare instances both tints are seen, producing an exceedingly beautiful effect. The thoracic light is subject to the will of the insect, but the abdominal is by some considered involuntary ; the former is intermittent, but the latter seems to be a constant red glare, which will illumi- nate the ground for the space of a yard square. There are more than a dozen other luminous elaters mentioned by Illiger, found in South America, where they fly during dusk and at night, generally remaining quiet during the day. These insects are used by the natives, confined under gauze, as ornaments for their head dresses and garments; they have been usefully employed by the Indians for the pur- poses of illumination in their dwellings and in their journeys; several, confined in a glass vessel, give light enough to read small print by. This is one of many instances in which an acquaintance with natural history has dissi- pated the fears of the superstitious; the deceit- ful light of supposed malignant spirits has be- come the beautiful radiation of an insect sport- ing amid its inoffensive companions. These insects may be kept for weeks, if fed on sugar cane, and placed in damp moss ; their light is more powerful than that of the glowworm. The larvae of many elaters are also more or less luminous. In the adults both sexes are luminous. (See "American Naturalist," vol. ii., 1869, pp. 420-423.) The genus lampyris (Fab.) includes the fireflies of the United States and the glowworm of Europe ; they are char- acterized by soft and flexible bodies, straight and depressed ; there is no snout, and the head in the males is occupied almost entirely by the eyes, and is much concealed by the thorax ; the antennae are short, with cylindrical and compressed articulations; the abdomen is ser- rated on the sides ; the elytra are coriaceous, and the legs simple; the females have only rudiments of elytra at the base of the ab- domen. The glowworms of Europe, L. noc-
