JULY. 



2/^ 



made of various sizes. In the one from which the first sketch was taken, 

 the tank which contains the water in which are the aquatic plants, 

 fishes, mollusks, and insects is about twelve inches in diameter and 

 about nine inches deep ; near the top in the inside is a flange with a 

 groove, into which runs the condensed water from the bell-glass, which 

 forms the Wardian case for the Ferns, Lycopods, &c. ; from the groove 

 it descends to the tank below. Into the centre of this vessel I put the 

 glass pedestal. I then cover the bottom with about 2| inches of fresh, 



but not very rich soil, in which I plant my aquatics: I use for this 

 purpose Valisneria spiralis, Aponogeton distachyon, Nymphsea odorata 

 minor, and N. macrantha. On tlie soil I put one inch of well washed 

 flints, or sea gravel, which prevents the insects or mollusks from makmg 

 the water toul. 1 then introduce the water through a fine rose to about 

 four or five inches deep, into which I put gold fish (small) or stickle- 

 backs, or any other small fish, mollusks, Succinea putiis, Planorbis 

 corneus, carinatus, and marginalis, Cyclas rivicola and cornea ; msects 

 —any species of Colymbetes, Hygrotu?, Hadaticus, Gyrnius, and 

 several other aquatic genera ; care nmst be taken not to introduce any 

 of the large carnivorous larvse. I then prepare for introducing the 



