24 Transactions of the Society. 
The two eels of undeterminable sex belonged to the groups V and 
VIII. 
Group 
V 
VIII 
Length in cm. .. 
21 
26 
D 
! 4 
6 
Although I have not been able to examine a larger number of 
eels from this pond, it is sufficient to show that their growth is 
very slow indeed. 
Usually one finds a considerable difference between the males 
and females after the groups IV or V, but here we find eels of 
both sexes belonging to groups VIII and IX having the same 
length. In group VIII the males vary from 27-34 cm. and the 
females from 31-37 cm., and in group IX the males vary from 
31-37 cm. and the females from 28-40 cm. 
In group VIII 2 males and 2 females measure 33 cm., and in 
group IX 5 males and 4 females measure 34 cm., and 2 males and 
3 females 35 cm. We even find in group VIII a female measuring 
only 31 cm., and in group IX one even smaller, 28 cm. The 
smallest male of group VIII measured 25 cm., and of group IX 
30 cm. 
The largest females belonging to groups X-XV, measuring from 
45-49 cm., have an extraordinarily slow growth even then. 
Under favourable conditions the eel can grow fast, and Marcus 
gives an example of elvers taken from the Severn and sent to the 
Paprotker Lake in East Prussia, where in about 4\ years the 
females grew to 50 cm., and I have seen in Spain females from 
45-55 cm. belonging to the group VII. 
It would not be possible to find out even very approximately 
the age of these eels by the zones on their scales, as the difference 
increases so greatly in the older age groups. 
The only member of group V showed a difference of 4 zones, 
but later we find up to 10. 
It is difficult to count accurately the zones of the otoliths of 
large eels, as they are so close together ; but there is no doubt that 
eels can live to a great age, growing to a great size like those large 
females modelled in the Science Museum and the Natural History 
Museum. 
The French naturalist Dareste kept an eel in captivity for over 
thirty years, and obviously the animal must have been some years 
old before he had it. 
That eels can live under very unfavourable conditions is 
proved by the experiment of my late friend Professor Jung, of 
Geneva, who kept an eel over four years without food. 
