34 



RIO DE JANEIRO. May — June, 1832. 



water, and sends forth a pleasing chirp. When several were 

 together they sung in harmony on different notes. Various 

 cicadce and crickets, at the same time, kept up a ceaseless 

 shrill cry, but which, softened by the distance, was not un- 

 pleasant. Every evening after dark this great concert com- 

 menced ; and often have I sat listening to it, until my atten- 

 tion has been drawn away by some curious passing insect. 



At these times the fireflies are seen* flitting about from 

 hedge to hedge. All that I caught belonged to the family of 

 Lampyridce, or glowworms, and the greater number were 

 Lampyris occidentalis. I found that this insect emitted the 

 most brilliant flashes when irritated : in the intervals the ab- 

 dominal rings were obscured. The flash was almost co- 

 instantaneous in the two rings, but it was first just percep- 

 tible in the anterior one. The shining matter was fluid and 

 very adhesive : little spots, where the skin had been torn, 

 continued bright with a slight scintillation, whilst the unin- 

 jured parts were obscured. When the insect was decapitated 

 the rings remained uninterruptedly bright, but not so brilliant 

 as before : local irritation wdth a needle always increased the 

 vividness of the light. The rings in one instance retained 

 their luminous property nearly twenty -four hours after the 

 death of the insect. From these facts it would appear pro- 

 bable, that the animal has only the power of concealing or 

 extinguishing the light for short intervals, and that at other 

 times the display is involuntary. On the muddy and wet 

 gravel- walks I found the larvee of this lampyris in great num- 

 bers : they resembled in general form the female of the Eng- 

 lish glowworm. These larvse possessed but feeble luminous 

 powers ; very differently from their parents, on the slightest 

 touch they feigned death, and ceased to shine ; nor did irrita- 

 tion excite any fresh display. I kept several of them alive for 



* On a dark night the light could be seen at about two hundred paces 

 distant. It is remarkable that in all the glowworms, shining elaters, and 

 various marine animals, which I have observed (such as the Crustacea, 

 medusae, nereidse, a coralline of the genus Clytia, and Pyrosoma), the light 

 has been of a well-marked green colour. 



