718 Mr. E. Ernest Green on 



Dioptoma adamsi, Pascoe. 



Of this insect, Dr. Sharp remarks (Camb. Nat. Hist., 

 Insects, Part II, p. 252) : " Nothing is known as to the 

 habits of this curiosity, not even whether it is luminous 

 in one or both sexes." 



I am now in a position to state definitely that Dioptoma 

 is luminous, in both sexes. On the 12th of this month 

 (Sept. 1912) I observed a glow-worm displaying its light 

 and evidently signalling for the male. The hinder part 

 of her body was recurved over the back, so that the large 

 sub-terminal photogenic organ was fully exposed. While 

 examining the female (without disturbing her) I witnessed 

 the advent of the male. His approach was not heralded 

 by any display of fireworks on his part ; but his arrival 

 caused a partial eclipse of the luminous disc on the female, 

 and her tail was immediately turned down to the normal 

 position. On boxing the specimens, I found the male 

 in co'itu, and discovered that I had captured the two sexes 

 of Dioptoma adamsi. 



Later, when examining my captures in the dark, I was 

 interested to observe that the male Diojjtoma (hitherto sup- 

 posed to be non-luminous) displays — under sexual excite- 

 ment — a brilliant series of lights of an emerald green colour. 

 There is a transverse series of 4 luminous spots along the 

 posterior margin of the prothorax ; a marginal abdominal 

 series of 8 on each side ; and two converging dorsal series 

 (of 3 points) on the hinder segments of the abdomen. It 

 is possible that this dorsal series may extend towards the 

 base of the abdomen, but the other spots would be eclipsed 

 by the opaque elytra. When viewed from below, inter- 

 mittent flashes appeared to emanate from the ventral area 

 of the thorax, but I was unable to locate their exact 

 position. 



The accompanying diagram (Plate LXXXVI, Fig. 2) 

 represents a dorsal view of the male Dioptoma, with 

 elytron and wing removed on one side, to show the 

 position of the luminous spots, I cannot guarantee the 

 absolute accuracy of the position of each spot, as it is 

 difficult to determine the segments of the living insect — 

 when examined in the dark ; but the number of visible 

 luminous points was verified several times. 



The female Dioptoma is an elongate apterous grub-like 

 insect ; the body sub-cylindrical, slightly broader than 

 deep ; the segments approximately of equal width, except 



