396 RADIATA. 



sel's wake, and especially just beneath her stern, in 

 the eddies made by the motion of the rudder ; and 

 perhaps those fitful flashes which now and then gleam 

 over the rising waves may have a similar origin. 



Of the remaining Acalepha, we shall notice only 

 one species, the PhysaUs* Pelagica, familiarly known 

 to seamen by the name of the Portuguese man-of- 

 war. In the tropical parts of the Atlantic this lovely 

 little creature abounds, looking at a short distance 

 exactly like a child's mimic ship, and attracts our 

 wonder and admiration to see so delicate and frail 

 a bark breasting the broad billows, as it seems that 

 the first breaking sea must inevitably overwhelm 

 and dash it to pieces. Yet, there it floats and 

 dances, now on the curling crest, now in the deep 

 hollow, in spite of wind and wave. Often, when 

 passing just under the lee of a vessel, the sudden 

 lull made by the interposition of so great a body 

 between it and the wind will cause it momentarily 

 to lie flat on the water, but it instantly resumes its 

 upright position. We have never made a voyage 

 without seeing these creatures in greater or less 

 number, but nowhere in such profusion as in the 

 Gulf of Mexico. In rounding the Florida Reef, 

 we were once nearly a whole day sailing through 

 a fleet of them, which studded the smooth sea as 

 far as the eye could reach. They were of all sizes, 

 from an inch in length to a foot or more. When 

 examined closely, the animal is seen to consist of 

 an oblong transparent bladder, pinched up at the 



* $virz*.ts, physalis, a bubble. 



