THE FRESH-WATER AQUARIUM. 
BY CHARLES B. BRIGHAM., 
[Concluded from page 490, of Vol. iii.] 
A very valuable addition to the specimens of an aquarium 
may be found in what are called the cray-fishes or fresh- 
water lobsters. These little animals so closely resembling 
their salt-water relations can be kept without much trouble 
in the general collection. They are natives of most parts of 
the country, though rare or limited in their habitat in New 
England. In New York they are abundant in the gravelly 
brooks and streams, especially in those near Trenton Falls. A 
- careful observer will, as wading into the water he searches for 
them, see two claws just visible in a hole in the sand or under 
the edge of a rock ; and if he can hedge the hiding place around 
with his net, and also possibly his straw hat, and then give 
the desired specimen a slight stimulus with his hand, he will 
find of a sudden his cray-fish resting quietly in the trap he 
has set. So quick are their motions that one has to keep a 
sharp lookout for them or they will escape; the average 
length of those found near Trenton Falls is about two 
inches. They are quite hardy, with this exception that they 
cannot bear water which is much above the normal tempera- 
ture. In the summer time if the tank is so placed that the 
sun shines upon it too forcibly, or for too long a time, we 
shall probably find the eray-fish resting motionless upon the 
gravel with its claws and tail extended and its body some- 
what swollen. If this state of things has not existed too 
long a time, immediate removal to cold water may revive 
the unfortunate victim by degrees. Some day, after the 
cray-fish has been a quiet inmate of the aquarium for some 
time, we shall be astonished in finding apparently two cray- 
fishes instead of one. Closer examination will diselose the 
faet that one of them is merely the cast-off shell of the 
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