36 
. Support for apparatus. 
. Balanced beam. 
Hm Co v9 
. Tumbling box. At c a brass rod is rigidly fixed 
working freely in hgnum vite ‘bearings fastened 
to the frame. . aB=35} inches, ac=27} inches, 
cb=9¥} inches, Bp=11 inches. Width=12 inches. 
5. Wires to rods. 
6. End view of hatching tanks, containing little 
‘boxes for eggs. 
i. Waste pipes leading into main pipe, taking water 
to tumbling box. 
8 
End view of top and bottom of main suspender. 
6 End view of suspenders of framework for wires and 
tumbling box. The suspender to the tumbling 
box works through a guide (gq). 
¢ Side view of tumbling box in its frame. 
NoTE ON THE SPAWNING OF THE MussEL (MyTILUS EDULIS), 
By A. .Scorr: 
The determination of the spawning period of the mussel 
on the Lancashire coast has occupied our attention for 
some time. Hitherto we have mainly examined the con- 
dition of the reproductive organs, both im sitw in the 
living animal, and by thin sections of prepared material 
during periods of twelve months. Tow-nettings from the 
vicinity of the beds have also been examined for the 
larvee. These investigations enabled us, approximately, 
to state when the eggs were shed. It is obvious, however, 
that all the information regarding the actual spawning, 
the fertilisation of the eggs, and the period that elapses 
before the resulting embryos become free-swimming 
larvee can only be ascertained by carefully observing the 
living animal. It is not possible to do this under natural 
