THE MARINE AQUAKIUM. 129 



After the crustaccous we come to thoso more important 

 scavengers who keep the glass of our tank clean and bright, 

 the Molluscs. The first of these which will be mentioned, 

 because the most common, as it is picked up all along our 

 shores, is the Buccinum obsoktum (Plate IX., Fig. 2). 



It is the empty shell of this species that the small her- 

 mit crab inhabits, in preference to any other. The color of 

 the shell is dark olive, or reddish brown, and the interior 

 of the lip a purple black. In length, it seldom exceeds 

 from half to three-quarters of an inch, although sometimes 

 it is found an inch long. It is extremely voracious ; and, 

 therefore, makes a good servant for the tank, projecting 

 its trunk from the shell and mowing the confervae from off 

 the glass — with a motion very much resembling that used 

 by a man when mowing — as the animal swings his trunk 

 from side to side. 



The European Whelk (B. undaium) is found sparingly 

 with us. It is highly recommended by English writers as 

 a scavenger for the tank. 



Natica duplicata (Plate IX., Fig. 4), is a very common 

 shell on our coast, as we have a right to suppose, because 

 we find hermit-crabs frequently inhabiting its shell. 



Pynda canalicuhta (Plate IX., Fig. 1), is another com- 

 mon shell that hermits sometimes take a fancy to. It is 

 kuow under the name of the Winkle, and is occasionally eaten. 



Fusils cincreus (Plate IX., Fig. 3), is, also, a common 

 coast shell ; and is known under the name of the Drill, by 

 our oystermen. It is said to be very destructive to the 

 oyster by piercing or drilling small holes through the shell 

 and destroying the auimal. The means by which this is 



