THE WATER CABINET. 113 
near rivers; the small tributaries of the Lea, and the 
dykes that abound in the marshes at Tottenham, supply 
me with specimens whenever I seek them. 
Among the water-worms most easily obtained, the hair- 
like Gordius aquaticus (Linneus), and the curiously- 
formed Nais, may be recommended as curious and inter- 
esting. The latter requires a bottom of sand in which to 
burrow, and should be covered with only a few inches of 
water. When it takes to its new home, it plunges its 
body into the sand or mud, and extends its telescope- 
tail upwards to the surface for air, adapting its length to 
the depth of the water. 
The generation and development of reptilia and mol- 
lusca may be better studied by the use of jars for the 
specimens, than by their immersion in the aquarium. 
Tadpoles, the larva of newts, and the spawn of mollusks, 
may be preserved in the cabinet for purposes of study, 
much better than in the tank; each species being separate 
in a bright and portable vessel, every minute change can 
be observed, and a lens applied at any time, or the spe- 
cimens removed for close inspection without difficulty. 
I find it a good practice to remove any spawn, which may 
be deposited on the large vessels, to the small jars on my 
shelves. There the little Lymnea and Planorbis are 
developed in hundreds, without molestation ; and if in- 
crease of Paludina vivipara be required, a jar is at once 
converted into a breeding tank by throwing a couple into 
it, with a bunch of Callitriche, and any vegetable waste 
from the tanks. In the aquarium, the young mollusks 
are devoured almost as soon as they are born; and the 
I 
