XXXVl 



observed, the light has been of a well-marked green colour. All 

 the fire-flies which I caught here belonged to the Lampyridce (in 

 which family the English glow-worm is included), and the greater 

 number of specimens 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 adhesive ; little spots, where the skin had been 

 torn, continued bright, with a slight scintillation, whilst the 

 uninjured parts were obscured. When the insect was decapi- 

 tated the rings remained uninterruptedly bright, but not so 

 l)rilliant 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 ;i.ppear 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 

 larvffi of this Lampyris in great numbers ; they resembled in 

 general form the female of the English glow-worm. These larvae 

 possessed but feeble luminous powers ; very difierently 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, 

 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 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 b}' 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 



