48 
distinctive characters which he notices are the relative lengths of 
the head and body, and the depth of the fish compared °to its 
length. Yarrell gives the number of vertebrae as 54, whereas in 
tlie common or northern herring they are 56. The colour of 
Leach 3 herring is brighter, and more decidedly blue. There is 
also a difference in the scales, which are comparatively larger in 
Leach’s herring. 
“As regards the measurements, it is obvious, that if, as I ^ 
believe, Leach’s herring is an immature form, the ratio would alter i 
with increased growth. So also would the colour with the age of i 
the fish, and Avith the period of fecundation. ° 
Ihe difference then rests solely on the number of vertebrae. 
On examining (Jan. 27th, 1864) a number of Leach’s herring full 
of ova, I found that the measurements were someAvhat different 
from those given by Yarrell. The comparative length of head and 
body Avere as 1 — 3^ — 3| in all cases. Depth to length as 1 — 5| 
or 6, in those which had spaAvned, 1 — 4| in those Avith roe. Of 9 
fish examined Avith reference to the number of vertebrae 4 had 55. 
2 had 54. 3 had 56. 
“ In some of those AAdiich had less than 56 vertebrae I was able to 
discern one or tAVo Avhich Avere rudimentary or abortive, thus showing 
thavt 56 is really the normal number as in the northern herring. 
“ 1 he position of the dorsal fin noticed by Yarrell, AA'ould also 
vary Avith the groAvth of the fish. Subsetpient observations at a 
later period of the year shoAved a marked alteration in the compa- 
rative measurements, and a nearer approximation to those found 
in the common herring.” 
D 
These observations Avere forivarded, together with specimens, 
to Mr. Couch, of Polperro. 
In reply j\tr. Couch says : — 
“Polperro, Peb. 13th, 1864. 
“ It may be a matter of curiosity to you to be j 
informed, that on the 6th of this month I made the following note 
in my Journal. ‘A large herring, male, Avith milt of full size of 
development— herrings seem in tolerable abundance— the fact of 
their haAung fully enlarged milt and roc is a reply to one of i^Ir. 
Yarrell’s arguments for Mr. Leach’s herring being a separate 
species, by breeding at that time, but is it a good species 1 ’ ” 
1 
