30 RIO DE JANEIRO. [chap. ii. 



(such as the Crustacea, medusae, nereidse, a coralline of the genus 

 Clytia, and 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 Lampyridee (in which family the 

 English glowworm is included), and the greater number of spe- 

 cimens were of Lampyris occidentalis.* 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 ad- 

 hesive : little spots, where the skin had been torn, continued 

 bright with a slight scintillation, whilst the uninjured parts were 

 obscured. "When the insect was decapitated the rings remained 

 uninterruptedly bright, but not so brilliant as before : local irri- 

 tation 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 fqr short inter- 

 vals, 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 re- 

 peatedly 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, notwithstanding 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 appa- 

 rently as a guide. 



* 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- 

 ance. 



