SB A -A CORNS. 



hairs, converting them into veritable brushes, which, 

 like the proverbial broom of Mrs. Partington, are 

 really employed in sweeping the waters. You can 

 guess the use of these plumes, though you may not 

 so readily arrive at a first conception of their nature. 

 They are the commissariat officials of the sea-acorn's 

 economy for under this name you must know the 

 shells which encrust the rocks, stones, and oysters 

 everywhere. By aid of its " feelers," the sea-acorn 

 sweeps into its mouth the food-particles on which it 

 lives. 



A most effective brush must these plumes con- 

 stitute, seeing that they number some twenty-four in 

 all, each of the original twelve being double in nature. 

 It is more than probable that these organs, forming 

 what has been named 

 the " glass hand " of the 

 sea-acorn, also serve for 

 breathing purposes, al- 

 though inside the shell 

 we certainly light upon 

 structures believed to re- 

 present gills. Still, from 

 their incessant waving in 

 the clear water, and from 

 the obvious opportunity 

 thus afforded of bring- 

 ing the blood of our 

 acorn in contact with the vivifying oxygen of the sea, 

 we may assume with safety that the plumes of the 

 "glass-hand" play a part, at least, in renewing the 

 vital fluid of the miniature frame. 



I tap lightly on the stone which contains our 

 colony of sea- acorns, and in a moment you observe 



Fig. 2. Balanus Hameri : a Sea- 

 Acorn viewed from the side. 



