The Age and Growth of some Eels from a Worcestershire Pond. 1 5 
It is possible to destroy the otoliths by boiling with caustic 
potash or soda. 
0$. One can extract them in this way, as the bones of the skull 
are attacked more quickly than the otoliths, but I do not recom- 
mend it, as often the otoliths are damaged if it is not carried out 
with the greatest care. I myself have spoiled much valuable 
material in this manner before learning better. 
It is not easy to find exact indications as to the preparation of 
the otoliths of the eel, and it cost me some trouble to find it out. 
I prepare the otoliths in the following manner : — 
As the lower jaws are of no use, they can be removed at once, 
and the head is now cut off at the beginning of Ihe gills. If one 
is collecting material in various localities, each skull can be wrapped 
up in a small linen square tied up with thread, together with a 
parchment label on which is written with Indian ink the number 
and locality of specimen. 
Each ten skulls are wrapped up in a larger linen square 
marked with the locality and the Roman numbers I, II, III, etc., 
which indicate that the packet contains Nos. 1-10, 11-20, 21-30, 
etc., of a locality. 
The skulls can be left in 70° alcohol till wanted. Of course 
