44 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
of barked bolting silk, having about 40 threads to the 
inch. In the centre of one end of the box is a shoot made 
of sheet brass 3 inches wide, 4 inch deep and 14 inch long. 
This fits below the shoot in the transverse partition 
between the compartments of the tank, to which the 
hatching box is attached by two leather hinges fastened 
with copper tacks. A short length of brass wire, with 
the ends bent at right angles, is driven into the top edge 
of each box which is nearest to the longitudinal partition. 
This wire receives the corresponding transverse rod of the 
hinged iron bar, when the latter falls for the purpose of 
depressing the floating box. (See the figs.). 
The supply of sea-water passes from the large 
outside storage tanks (see photograph, fig. 8) through a 
2-inch galvanised iron pipe, which enters the building at 
the north-west corner (SP in the figures). From thence a 
1i-inch pipe carries the supply to the aquarium and 
‘laboratories, and from this a branch of the same size 
(SP’) supphes the hatchery. Here the water first enters 
the filter. his is a box made of wood 1} inches thick, 
and coated inside with a mixture of tar and pitch. Its 
length over all is 4 feet 6 inches, width 2 feet 4 inches, and 
depth inside 1 foot 4 inches. At a depth of 9 inches from 
the top a flange of wood, 2 inches wide and 1 inch thick, 
runs round the inside of the box, and resting immediately 
on this is a rubber washer of the same width as the flange 
and + inch thick. Upon this rests a frame of wood 4 feet 
3 inches long, 2 feet 2? inch wide and 1 inch thick, and 
strengthened by two equidistant cross pieces. To this 
frame five thicknesses of white Turkey towelling are 
fastened with ~ inch copper tacks about 1 inch apart all 
the way round, and a corresponding length of galvanised 
wire netting of $-inch mesh is fastened over the towelling 
to keep it in place. Above the frame is another rubber 
