240 
l J art III. — Tenth Annual Report 
Further investigation has confirmed the proportions given in the previous 
paper where the number of specimens was at all large, with one notable 
exception, viz., the long rough dab. From the anomaly presented by the 
great disproportion of males in the previous enquiry (1 to 8), I was 
induced to have special hauls made with a small-meshed net. These have 
not perhaps been sufficient to elucidate the sexual proportions of this species 
exactly, but they show that the males are much more numerous than was 
supposed, A number of the males are very small, and they had escaped 
through the ordinary net used previously, It is a curious fact that the 
male long rough dab" may reach sexual maturity when scarcely five inches 
long — some specimens were nearly half-matured when only three and a 
half inches in length; and a ripe female may be over sixteen inches. 
The same appears to be the case, but to a much less extent, with the 
common dab. The contrary anomaly of the flounders — excess of males — 
was likewise specially investigated, and the previous results fully confirmed. 
It is remarkable that this fish alone, among those producing pelagic ova, 
should have the males in greater numbers than the females j probably it is 
owing to the exceptional fecundity of the female, as suggested in my paper 
on Fecundity in last year's Report (p. 247). 
An interesting point brought out in this table is the excess of females 
in fish producing pelagic ova, and the excess of males in fish producing 
demersal ova. In the Angler the males are also in excess. In studying 
the~fecundity of different species I was struck with this circumstance, and 
made some observations as to the relative weight and volume of the testes 
and ovaries in the two classes referred to, and the results help to explain, 
I believe, the disparity both in number and size between the sexes. I 
give a few examples in the annexed table (Table YIL). 
Among flat-fish especially, the disparity between the size or volume of 
the testes and ovaries is very great, as may be seen if ratios are made. 
For example, in the plaice, in the instances given, the weight of the 
female reproductive organ is more than twenty-six times that of the male 
reproductive organ ; in the flounder it is about forty times, and so on. 
Probably with the common sole the disparity is much greater. Among 
some of the Gadidae, the volume of the testis is relatively greater, 
especially in large individuals.* 
On the other hand, among fish with demersal ova, the volume of the 
male organ is generally relatively greater — in many cases it is actually 
heavier than the ovaries {e.g., herring, sand-eel). 
Now, it appears to me that a certain relation can be established between 
these facts and the proportional number and sizes of the sexes, looking at 
the matter as a question of stowage of the quantity of the reproductive 
material required. The females in fish producing pelagic ova require all 
the space for the ripe ovaries which distend their bodies, while the com- 
paratively small testes take up little room. Hence, in such fish this 
relationship is shown in the sexual proportions — sometimes by a greater 
number of females, or by their greater size, and generally in both 
these ways, but in different ratios in different species. Among fish 
with demersal ova we may have the testes heavier than the ovaries, as just 
said, and the proportional numbers of the sexes may be in such cases 
pretty equal. But in the lumpsucker, where the male is smaller than the 
female, and the testes smaller than the ovary, we find the males far more 
numerous than the females. Why should the amount of reproductive 
* Mr Robert Duthie, the Assistant Officer at Shetland, when endeavouring to 
procure fertilised ova of the torsk, wrote that while there was abundance of ripe 
females, all the males landed were immature, possessing very small testes. When 
advised to tease up a portion of the testes, the ova were successfully fertilised, the 
small male organ being normal. 
