SUBTERRANEAN LIOHT-QIVERS. 39 



that the medium in which the light-giver lives seems to have 

 ignited, and to be slowly consuming its dependents. 



It has been noticed, according to W. C. Mcintosh, that an 

 odor accompanies this display, resembhng somewhat that pro- 

 duced by phosphorus in combustion. We have noticed that 

 many worms have a peculiar odor when handled, though 

 not quite of this character. 



The most brilliant of all these light-givers is Polydrrus, 

 which emits over its entire surface a vivid pale-bluish light, 

 marking it as one of the most beautiful of its kind; while 

 Sagitta and many more add to the wonders in this generally 

 considered uninteresting group of animals.^ 



