MARINE BIOLOGICAL STATION AT PORT ERIN. AD5 
washer and then a second similar frame. A spar of wood, 
4x2 inches (SR in fig. 1), rests on the top of the box 
and is securely braced to the ends. To its lower face are 
hinged four pieces of hard wood, 6} x 21x11 inches, at 
distances corresponding to the ends and cross bars of the 
filter frames. When these hang vertically their rounded 
ends are firmly pressed against the frames, and the 
pressure can be increased by the interposition of thin 
wedges of hard wood. Water is admitted to the filter 
through the valve in the supply pipe SP’, and the flow is 
Fic. 8, The fish-pond, and the two large outside storage tanks— 
photographed from the cliff behind the station, 
regulated by a butterfly valve immediately above, the 
movements of which are controlled by a ball-tap arrange- 
ment, the details of which will be readily understood by 
reference to fig. 6. After passing through the filter 
frames the water leaves the filter box through the 1}-inch 
pipe SP” and is distributed to the hatching tanks, where 
it flows downward from compartment to compartment, so 
as to fill and surround the floating boxes containing the 
ova. From the lower end of each hatching tank it flows 
through a lead pipe of 1 inch bore (LP) to a 1) inch 
