of the Fishery Board for Scotland. 



333 



The herrings numbered 1155, of which 514 were females and 641 

 were males. Most of them were spawning, but 40 females and 43 

 males were spent. The herrings as a whole were smaller than those got 

 in February. Whether this was due to any extent to their having been 

 soaking in weak formaline solution is doubtful ; my experience with 

 other fishes is that they do not appreciably diminish in length under 

 such circumstances. The fact that they were measured by another 

 person has to be kept in view, but, making all due allowances, I think 

 it may be assumed that these herrings were on the whole smaller than 

 those in the previous month. 



The table of measurements and the curve (Plate XIX.) show that the 

 bulk of the herrings was composed of two annual series, bub it is not 

 very clear where the division occurs in this case. Theoretically, it 

 should be about 24*5cm., and a consideration of the curves and tables 

 suggests that it should be placed at 244mm. ; but the division is some- 

 what arbitrary. The separate curves for the sexes dees not help much, 

 except in the case of the males, where there are cusps or modes at 

 23cm. and 25cm., the depression being at 24cm. 



To this series belong 256 females and 319 males. Both have a similar 

 range, from 211mm. to 244mm. (but the latter is no doubt greater, and 

 possibly goes to over 25cm.) ; the modal size for each may be put at 

 23'5cm. (9 J inches); the means are 227-5mm. (or, if the series is 

 extended to 254mm. — a centimetre more — it is 232'5mm.); the computed 

 average sizes are, for females 232*8mm., and for the males 232 2mm. 



Combining both sexes, the group of 575 herrings have the same range 

 as above, the same modes and means, and the avarage size is 232-5mm,, 

 or 9 inches. 



The second series of herrings begins about 245mm., or, if extended 

 for 1cm. backwards, at 235mm. (9 j inches). Where it ends is not so 

 clear. The 2mm. grouping is as follows : — 



267 269 271 273 275 277 279 281 283 285 287 289 291 

 18 14 13 12 5 4~ 2 2 1 - 2 I Z 



and the millimetre measurements are : — 



271 272 273 274 275 276 277 278 279 280 281 282 283 284 28 5 

 ~8 8 4 2 3 2 2 L 1 I I - i I I 



It might end at 281mm., or 274mm., or at 277mm., and I take the latter 

 (10if inches). 



To this group belong 252 females and 317 males. Both have the 

 same range, 245mm. (or 235mm.) to 277mm.; the modal size is about 

 25cm. (9^ inches); the means are 261mm. (or 256mm.); and the com- 

 puted averages are, for the males 252"7mm. (almost 10 inches), and for 

 the females 254' 1mm. (10 inches). The group of 569 herrings has 

 the same range, mode, and mean as described, and the computed average 

 is 253*5mm. 



The difference between the first and the second series in the March 

 herrings (on the averages) is, for females' 2l'3mm., for males 19-9mm., 

 and for the series combined 21 -0mm. 



There were other eleven herrings of larger size in the collection, viz., 

 six females, measuring 281mm., 283mm., 287mm., 288mm., 324mm., 

 and 325mm.; and five males, measuring 278mm., 279mm., 280mm., 

 287mm., and 304mm. 



These obviously belong to different annual series. It is very probable 

 that the herring at 304mm. represents an older group than those smaller, 

 while the two large females (12| inches) must be some years older. 



