PELAGIC FLOATING CRUSTACEA 



147 



The same result is produced if the surface is increased 

 by outstanding spines or hairs, just as, for instance, 

 a downy feather sinks slowly through the air, but 



Fig. 51 — The Nauplids Larva of a Species of Barnacle of 

 THE Family Lepadid^, showing greatly-developed Spines. 

 From a Specimen taken in the Atlantic Ocean, near 

 Madeira, x ii. (After Chun.) 



drops rapidly if it is rolled into a ball between the 

 fingers. This is, no doubt, one function of the 

 spines with which plankton Crustacea, and particu- 

 larly larvae, are frequently provided, though they 



