332 Part I1I.— Twenty-fourth Annual Report 
These spring herrings are five years of age, and they appear to be the 
first annual series which attains maturity. 
The second group of herrings comprised 248 females and 282 males. 
The beginning of the series is where the fusion with the younger series 
occurs, at 25l1mm., but it probably extends back to about 23°5cm. 
(9; inches), judging from the form of the curve. The place where it 
ends is not so immediately clear. The following shows the arrangement 
in 2mm. groups :— 
270 272 274 276 278 280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 
Hern] ese Lil 7 LL eae cate ek LD een em) eee ent ee | ea 
Male, j= (14'S Fite e8: 922) NO) Bae aS =e += Ne 
20). [SALShISh eS 4s) OO neo ee ) -— 
And the measurements under the millimetres are these :— 
276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 
Female, “30 12d) ale oe aL) ee POLS a ool P= 7 2 
Male;..- 980.46. 0 G20 Dame a y= oe oe BO Oy Ie he 
Oye al Gp SheeS MOT =) OMe O men (Tao ae Ot maaes Be 
It appears from this that the group terminates at 281mm. (11,5 
inches), the rest of the herrings belonging to, at least, one older group. 
The modal size is 257mm. (103 inches), the mean is 266mm. (or 261mm. 
on the extension of the group back to 240mm.), and the average as com- 
puted is 262:1mm. (10,°, inches). 
The males begin and end like the females, have exactly the same 
modal size, while the computed size is 261mm. 
The group comprising both sexes contains 530 herrings, with the 
same range, modes, and means, the computed average size being 261‘5mm. 
These herrings are six years of age. 
The rest of the herrings numbered 10 females and 12 males; the 
former ranged in size from 283mm. to 305mm. (112 to 12 inches), and 
the latter practically the same, 283mm. to 304mm. These herrings are 
seven years old, and although the range of size shown is only 22mm. 
(=) 
and 2lram., it is probable, judging from the 2mm. table given above, that 
the three herrings at about Paelve inches (300mm., 304mm., 305mm.) 
are at least a year older still. Growth in length, as is well known, is 
much retarded when the fish attain to maturity and afterwards, as is 
shown, indeed, by comparing the modal sizes of the two series under 
discussion, the growth indicated in a year being only about 19mm. 
(? inch). ; 
Tt will be noticed that in both series the males are more numerous 
than the females, and that, while in the second or older series the size 
of the males and females is the same, the males in the first group are 
appreciably smaller than the females. In both lots of males of this 
series measured, the mode in the ‘Sem. curves is at 23°5em.; in the 
older group one of the modes is at 25°5cm.; and the other at 26cm. 
When all the males are considered together, the mode in the ‘bem. curve 
is at 23°5cm. in the younger group and at 25:5em. in the older group. 
In the two lots of females, the cusp in one case in the younger group 
was at 23-5em., and in the other at 24:‘5cm.; in the older group both 
the cusps or modes were at 25°5cm. 
There was thus a greater number of small males than of small females 
in the younger series, but this does not necessarily denote that the 
male reaches maturity at a smaller size than the female. 
In March, another lot of these spring herrings from the Forth were 
measured. They were forwarded to the laboratory, and placed in weak 
formaline solution for a time; they were measured by the laboratory 
attendant, who also determined the sexes in most of them by opening 
the fish ; doubtful cases were determined by myself. 
