44 ON LUMINOUS ANIMALS* 



In the elater igiiitus, the masses of luminous substance 

 are extremely irregular in their figure: they are situate 

 nearly at the posterior angles of the corselet, and are more 

 loose in their texture than the oval masses of the noctilucus, 

 resembling rather in composition the interstitial substance, 

 which surronnds these masses in that species. The shell 

 of the corselet is somewhat thinner, and more transparent 

 along both sides of the margin, than at other places; but 

 it is not, as in the noctilucus, elevated, and peculiarly 

 clear and thin, immediately over the seat of the luminous 

 organ; consequently the light emitted by the elater ignitus 

 cannot be very brilliant. 



1 have not been able to procure any specimen of the 

 elater phosphorea : but from the accounts of naturalists it 

 appears to resemble in every re--.pect the elater noctilucus; 

 indeed I have great doubts of the phosphorea being a dis- 

 tinct species, 

 drgan in th» I have had an opportunity of examining, preserved in a 

 moist way, two species of fulgora, the candelaria and Ian* 

 ternaria. The light in this genus has been observed to issue 

 from the remarkable proboscis of the fore part of the head. 

 This part has always been described by authors as hollow, 

 or empty, which I have found to be perfectly correct; and 

 what is more extraordinary, that the cavity communicates 

 freely with the external air, by means of a chink or nar- 

 row aperture, placed on each side of the root of the pro- 

 boscis. This projection is covered internally by a mem- 

 brane, between which and the horny part, or shell, there 

 appears to be interposed a pale reddish coloured soft sub- 

 stance, that is arranged in the candelaria in broad lines or 

 stripes; but it is so thin, that I could not distinctly exa- 

 mine its structure, or absolutely determine, whether it 

 should be considered as a substance intended to furnish the 

 light of these insects, or the pigment upon which the co- 

 lour of the proboscis depends. 

 Pausus sph€ro- The globes of the antennsB constitute the organs of light 

 '^'^■^ in the pausus spherocerus. Dr. Afzelius, who discovered 



the luminous property in this species, compares them to 

 lanterns spreading a dim phosphoric light*, ^i^he rarity 



• Lin. Trans. Vol. IV. 



of 



