22 RIO DE JANEIRO. [CHAT. n. 



Pyrosoma), which I have observed, the light has been of a well-marked 

 green colour. All the fireflies, which I caught here, belonged to the 

 Lampyridae (in which family the English glowworm is included), and 

 the greater number of specimens were of Lampyris occidentalism* I 

 found that this insect emitted the most brilliant flashes when irritated : 

 in the intervals, the abdominal rings were obscured. The flash was 

 almost co-instantaneous in the two rings, but it was just perceptible 

 first 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 uninjured parts were obscured. 

 W.hen the insect wa"s decapitated the rings remained uninterruptedly 

 bright, but not so brilliant as before: local irritation with 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 probable, 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 larvae of this lampyris 

 in great numbers : they resembled in general form the female of the 

 English glowworm. These larvae possessed but feeble luminous 

 powers ; very differently from their parents, on the slightest touch 

 they feigned death, and ceased to shine; nor did irritation excite 

 any fresh display. I kept several of them alive for some time : their 

 tails are very singular organs, for they act, by a well-fitted contrivance, 

 as suckers or organs of attachment, and likewise as reservoirs for 

 saliva, or some such fluid. I repeatedly fed them on raw meat ; and 

 I invariably observed, that every now and then the extremity of the 

 tail was applied to the mouth, and a drop of fluid exuded on the 

 meat, which was then in the act of being consumed. The tail, not- 

 withstanding so much practice, does not seem to be able to find 

 its way to the mouth ; at least the neck was always touched first, and 

 apparently as a guide. 



When we were at Bahia, an elater or beetle (Pyrophorus luminosus, 

 Illig.) seemed the most common luminous insect The light in this 

 case was also rendered more brilliant by irritation. I amused myself 

 one day by observing the springing powers of this insect, which have 

 not, as it appears to me, been properly described.! The elater, when 

 placed on its back and preparing to spring, moved its head and thorax 

 backwards, so that the pectoral spine was drawn out, and rested on the 

 edge of its sheath. The same backward movement being continued, 

 the spine, by the full action of the muscles, was bent like a spring ; 

 and the insect at this moment rested on the extremity of its head and 

 wing-cases. The effort being suddenly relaxed, the head and thorax 

 flew up, and in consequence, the base of the wing-cases struck the 



* I am greatly indebted to Mr. Waterhouse for his kindness in naming 

 for me this and many other insects, and in giving me much valuable assist- 



f "Kirby's Entomology," vol II, p, 317, 



