The Age and Growth of some Eels from a Worcestershire Pond. 19 
the eel, but varies according to the faster or slower development 
of the various zones of the scales. 
The Roman figures I, II and III behind the number of 
zones of the scales indicate that there was a lesser or greater 
quantity of scales having this number of zones on the eels in 
question. For instance, 3 I means that there were not many 
scales with three zones, and that it needed some trouble to find 
them. 3 II means that there were a fair number of such scales, 
and that they could be found without difficulty. 3 III means 
that the majority of the scales examined had three zones. In 
some cases even practically all the scales may have the same 
number of zones, and one searches in vain for even one scale 
having one more zone. 
Sometimes one finds perhaps only 1-2 scales having the 
highest number of zones, and often the zone may be incomplete, 
forming a cap on the preceding zone, either internally or externally 
The eels belonged to the following age groups : — 
Group Y. 
Length Number of zones 
Number cm. on scales D 
77 21 1 4 
The only eel of this group I caught measured 21 cm., and it 
was impossible to determine its sex. There were numerous scales, 
but without any zones of growth, and D therefore was 4. 
Group YI. 
I was not fortunate enough to capture any eel of this group. 
Number 
2 
42 
Group YII. 
Males. 
Length Number of zones 
.cm. on scales D 
32 3 4 
30 3 4 
Two males, length 3Q-32 cm., D 4. Average length 31 cm. 
Females. 
Number 
Length 
cm. 
Number of zones 
on scales 
D 
37 
36 
3 III 
4 
29 
35 
3 II 
4 
38 
33 
3 II 
4 
25 
30 
3 I 
4 
Four females, length 30-36 cm., D 4. Average length 33*5 cm. 
