26 LIVING LIGHTS. 



If we could descend into these depths, we would find a 

 veritable forest, with branches seeming on fire; many of 

 the coral trees being from ten to fifteen feet in height, and 

 equally as wide, forming lanes and open pathways through 

 which the fishes pass, bathed in the wondrous light. That 

 this is not imagination is shown by the branches brought up 

 accidentally and by dredges; some limbs alone being four 

 feet in length, and stout in proportion. Specimens of these 

 forms can be seen in most of our museums of science ; some 

 sent by Dr. Holder from the Florida reef to the Museum of 

 Natural History, in Central Park, are surprisingly beautiful. 



More remarkable than the Gorgonias are the strange ani- 

 mals belonging to Pennatulidce,^^ known popularly as the 

 sea-pens (Plate VII., Fig. 2), from the resemblance of some 

 to a quill pen, — an abnormally large one, it must be con- 

 fessed. One of the most familiar forms is Pennatula phos- 

 phorea. When the animal is observed at night, and disturbed, 

 it emits quite a brilliant light. In specimens observed at 

 Oban by Professor Marchel, the more perfect females became 

 vividly phosphorescent when the leaves were gently irritated. 

 When the polyps were touched, they showed minute points 

 of light, which appeared over the whole surface, in rapid, 

 irregular coruscations. 



If one of these living pens can produce so interesting a 

 display, what must be the sight upon the bottom, where 

 myriads of these curious forms abound, either fixed or 

 moving ! 



It is not impossible that the light-emitting faculty of sea- 

 pens is under control; at least, they have their periods of 

 darkness and light. If a specimen which is not luminous 

 is disturbed, as we have seen, it immediately becomes so. If 



