ON LUMINOUS ANIMALS. 55. 



Fig. 13. Is an enlarged view of the inferior surface of 

 the abdomen of the lampyvis lucida, after the integumenjt 

 hud been removed, a aa represent the three masses of 

 luminous substance, which are applied to the three last 

 rings of the abdomen, bhb the arrangement of the cel- 

 lular or interstitial substance on the other abdominal rings, 

 which gives the pale colour to the whole belly of this 

 insect. 



Fig, 14. Represents the common glow-worm, with the 

 posterior portion on the back cut away to expose the sacs 

 of luminous matter in situ on the last ring of the belly. 

 a indicates the sac of one side; the intestine is seen to lie 

 between them. 



Fig. 15 and 16. Are the sacs of the glow-worm prodigT^ 

 dusly magnified to show their structure. Fig. 16 is cut 

 open to expose the luminous matter it contains; the coat of 

 the sac is still seen to preserve its figure. 



Fig, 17. Is the elater noctilucus, with the shell of the 

 corselet removed on one side, by which the organ of light 

 is uncovered, a the yellow transparent spot of the corselet. 

 h the oval mass of luminous substance surrounded by aH 

 irradiation of the interstitial substance.* c the ends of the 

 muscles which were on the inside of the corselet. 



Fig. 18i Is the posterior angle of the corselet of 'the 

 elater hoctilucus magnified. <i the radiated appearartce 

 which the interstitial substance has round the oval mass 

 of luminous matter. This mass is seen to contiist of a 

 number of smaller parts. 6 shows the appearance of the 

 interstitial substance, where it passes down between the 

 muscles, c the ends 6f the muscles of the back. ^ f he 

 shell of the corseleti '^ 



Fig. 19. Represeiits the elater ignitus. a is the mass of 

 luminous substance of one side, seen indistinctly through 

 the back of the seniitransparent portion of the corselet, h 

 is the luminous mas* of the other side, exposed by removing 

 a part of the shell of tlte corselet. 



VII. 



