742 Luminosity of Marine Animals. [December, 
further supports the view just put forward. Thus from the 
time of Pliny it has been known that Pholas dactylus is 
luminous, whilst the common P. crispata does not possess 
this property. Two Annelida, Harmothoe wibricata and 
Polynoe flaccosa, are both very common between high and 
low water-mark : they closely resemble each other in their 
habits and in their appearance, but the one .is brightly 
luminous, while the other has not a trace of this property. 
Instead of enticing other animals as their prey, or of being 
themselves more readily captured, the phosphorescent 
Annelida are often inhabitants of tubes or guests of star- 
fishes. In fadrt, in the various groups, we find every variety 
of vital conditions combined with the presence of phosphor- 
escence, so that the greatest care must be taken in drawing 
conclusions if they are to be of general applicability. 
