90 MARINE ANIMALS OF MASSACHUSETTS BAY. 



this effect is lost in a great degree, and it is not until you dip 

 your net fairly under the moonlit surface of the sea, that you 

 are aware how full of life it is. Occasionally one is tempted out 

 by the brilliancy of the phosphorescence, when the clou-ds are so 

 thick that water, sky, and land become one indiscriminate mass 

 of black, and the line of rocks can be discerned only by the vivid 

 flash of greenish golden light, when the breakers dash against 

 them. At such times there is something wild and weird in the 

 whole scene, which at once fascinates and appalls the imagination ; 

 one seems to be rocking above a volcano, for the surface around 

 is intensely black, except where fitful flashes or broad waves of 

 light break from the water under the motion of the boat or the 

 stroke of the oars. It was on a night like this, when the phos- 

 phorescence was unusually brilliant, and the sea as black as ink, 

 the surf breaking heavily and girdling the rocky shore with a wall 

 of fire, that our collector was so fortunate as to find in the rich 

 harvest he brought home the entirely new and exceedingly pretty 

 little floating Hydroid, described under the name of Xanomia 

 (Fig. 115). It was in its very infancy (Fig. 108), a mere bub- 

 ble, not yet possessed of the various appendages which eventually 

 make up its complex structure ; but it was nevertheless very im- 

 portant to have seen it in this early stage of its existence, since, 

 when a few full-grown specimens were found in the autumn, 

 which lived for some days in confinement and quietly allowed 

 their portraits to be taken (see Fig. 115), it was easy to connect 

 the adult animal with its younger phase of life and thus make a 

 complete history. 



Marine phosphorescence is no new topic, and we have dwelt too 

 long, perhaps, upon a phenomenon that every voyager has seen, 

 and many have described ; but its effect is very different, when 

 seen from the deck of a vessel, from its appearance as one floats 

 through its midst, distinguishing the very creatures that produce 

 it, and any account of the Medusae which did not include this 

 most characteristic feature would be incomplete. 



