38 



known to be luminous, but under the stimulus of sexual excitement, 

 it was observed to exhibit a row of luminous spots along each side 

 of the abdomen, as well as dorsal spots on the abdomen and across 

 the base of the thorax. 



I have recently received from my friend, Mr. Gairdner of Bangkok, 

 some females of a glow-worm which, he reports, turn up their tails 

 to exhibit the light in a similar way to Dioptonta. Like the female 

 Dioptuma, too, they are of a more degenerate type than Lanijjijris 

 females, the antennae and legs being small and feeble with a re- 

 duced number of joints. 



The species is also represented in the British Museum Collection 

 by some undetermined females, and some larva; from Perak must be 

 at least very closely allied. The latter have a well-developed, 

 probably luminous, plate on the ventral surface of each of the 

 abdominal segments from the 2nd to the 8th, an arrangement not 

 known among lampyrid larvae. The male of this species has not 

 yet been ascertained, but as Dioptoiua forms one of an anomalous 

 group of small genera, which for the most part are known only by- 

 the males, it is probable that it will turn out to be one of these. 



Allied to these and to the Lampyrid^e is another small family, the 

 Phengodidai, many of the members of which possess very remarkable 

 luminous properties. In Brazil and Argentina for example, is an 

 insect that on account of its peculiar scheme of luminosity, has long 

 been known as a "railway" larva. The head of this creature 

 glows brightly with a red light, like a live coal, which is more or 

 less intermittent in character, while along each side of the body is a 

 row of more constant lights, green or yellow, or even changing at 

 intervals from a bluish to a more yellow hue. For many years 

 these "railway" larvffi were nothing more than a puzzle to en- 

 tomologists. On account of their light-giving powers they were 

 usually considered to be lampyrid larvae, though nothing else like 

 them was known. Still less were they like the larva? of the only 

 other known luminous coleopterous family, the Elaterida?. The 

 astonishment was great when in 1885* it was announced that the 

 botanist, Hieronymus, had found one of these so-called "larvae" 

 mated with a beetle belonging to the genus Pliemjudes. Eggs were 

 obtained from it which in due course produced larva?, thus proving 

 that the supposed larva was in reality the sexually mature, though 

 degenerate and completely larviform, female of a beetle. 



We are now confronted with the very interesting question as to 

 whether the apterous, more or less larviform, state of the females of 

 many of these glow-worms is a primitive condition or the result 

 of degeneration from an earlier higher winged type. Rileyf states 

 that the female larva of Pliengoden laticoUh and Zarhipis ricersii, 

 both North American species, goes through a pseudo-pupal state 



* Haase, " Sitzung. Natur. Ges. Isis.," p. 10; and "Deutsche Ent. Zeit." 

 xxxii., p. 154 ; " Camb. Nat. Hist. Ins.," Pt. ii., p. 251. 

 t " Ent. Mo. Mag.," xxiv., 1887, p. 148. 



