4i Transactions. — Zoology. 



specimens and recorded them as dipterous larvae, but, through 

 pressure of other work, did not figure or carefully examine 

 them. 



Exactly a year later I had the insect again brought under 

 my notice during a conversation with Mr. E. Meyrick, who 

 told me that he had written a short note on the animal, which 

 is quoted in full in my pre\'ious paper (Trans., vol. xix., p. 62). 

 He stated as his opinion that the larva was referable to one of 

 the Staphylinidae (Coleoj)tera), and carnivorous. The light he 

 considered attracted, and the web entangled, minute insects 

 on which he supposed the larva to feed. It will be seen that 

 his supposition as to the nature of the insect is enth'ely con- 

 tradicted by subsequent investigation, whilst the latter con- 

 jecture has not in any way been corroborated, as we are still 

 entirely in the dark as to the use of either the web or the hght 

 to the larva. 



Dm-iug February and March, 1886, 1 instituted very careful 

 observations on the larvae, keeping several specimens in cap- 

 ti\aty. From these I ascertained that the light was not ex- 

 hibited at all regularly, sometimes being brightest at night, 

 and sometimes in the early morning hours. I have since 

 noticed that, in the natural state, the larvae shine most 

 brilliantly on dark damp nights with a light north-west 

 wind. 



The web referred to above is suspended in a rocky or earthy 

 niche in the banks of streams in the densest parts of the 

 forest. It consists of a thick glutinous thread stretched 

 across the niche, and supported by several smaller threads 

 running right and left, and attached to the sides and end of 

 the cavity. On this the larva invariably rests, but when 

 disturbed immediately glides back along the main thread, and 

 retreats into a hole which he has pro\'ided at the end of it. 

 From the lower side of this central thread numerous smaller 

 threads hang down, and are always covered with little globules 

 of v,-ater, resembling a number of minute silver-beaded neck- 

 laces, constituting a conspicuous, though apparently unim- 

 portant, portion of the insect's web. I should mention that 

 aU these thi-eads are constructed by the larva from a sticky 

 mucus exuded from the mouth. 



The organ which emits the light can easily be seen by a 

 reference to PI. YIIL, fig. 1. It is situated at the posterior ex- 

 tremity of the larva, and is a gelatinous and semi-transparent 

 structui'e, capable of a great diversity of form. It can be with- 

 drawn or extended at the will of the larva, which, however, can 

 immediately cease to shine without withdrawing it. This 

 action is most likely effected by shutting off the air from the 

 tracheae ramifying through the "light-organ," which, being, 

 no doubt, largely composed of phosphorus, only becomes 



