246 Part III. — Ninth Annual Report 
2. Fish with Pelagio Ova. 
Number 
Minimum 
Maximum 
Mean 
Species. 
Examined. 
Ratio. 
Ratio. 
Ratio. 
Cod, 
3 
12774 
280-91 
220-22 
Haddock, .... 
5 
111-11 
154-11 
126-90 
Wliiting, .... 
9 
35-66 
18174 
93-24 
Ling, 
Saitlie, .... 
4 
103-44 
181-79 
155-46 
2 
105-52 
107-73 
106-63 
Gurnard, .... 
3 
9976 
144-57 
128-73 
Halibut, .... 
2 
20-69 
4675 • 
33 72 
Turbot, .... 
4 
86-81 
135-57 
101-98 
Plaice, .... 
Flounder, .... 
5 
149-35 
359-54 
249-03 
3 
11371 
350-27 
263-44 
Long Rough Dab, . 
4 
102-17 
18079 
147-98 
A circumstance strongly impressed on my mind in the course of the 
investigation was the very different degree of ease, so to speak, with 
which the ova are carried in different species. In some, as in the plaice, 
flounder, and cod, there was very great distension of the surface over the 
ovaries. In the plaice, flounder, common sole, (fee, the ovaries are pro- 
longed backwards to nearly the root of the tail, and in the two former the 
tumidity of the surfaces is exceedingly great. In many cases, however, 
there is very little tumidity, as in the long rough dab, where the ovaries 
do not extend so far back, and are very slender. So also in the witch 
sole and others. 
The great size of the ovaries at maturity in some fishes causes compres- 
sion of the viscera. To this circumstance is probably due the well-known 
fact that some species refrain from food at this time. Mr John Murray, 
fishery officer, whom I asked, is of opinion that, among cod, more females 
than males are caught by baited hooks while the roes are maturing, and 
that during the spawning time more males are caught. On the other 
hand, I have found the stomach crammed with food in certain forms 
(Liparis, Coitus huhalis) carrying fully ripe ova. 
It would appear that the number of mature ova necessary to be pro- 
duced each season to maintain the position of the species can only be carried 
together in certain instances, such as in the lumpsucker and salmon, where 
the abdominal cavity is sufficiently capacious for the mass of large ova ; 
and in the herring and sparling, where the eggs are smaller and the 
numbers not large. In most cases it would be quite impossible for the 
fish to carry simultaneously, in the mature or perfect condition, all the 
eggs which the conditions of the struggle for existence have made it im- 
perative it should produce. For* instance, it is sbown below (p. 264) 
that the mature ovum of the plaice weighs about — j- of a grain, and that 
one female plaice, the gross weight of which was 4 lbs. 3 J oz., contained 
over 487,000 immature ova. The weight of this fish, when the ovaries 
were removed, was 3 lbs. 6| oz. (23,060 grains), and the weight of the ova 
which it carried, when fully ripened and mature, would be 4 lbs. 15| oz. 
(34,786 grains), or a pound and a half heavier than the body of the fish. 
Similar examples may be found among other species, possessing pelagic 
or demersal ova; e.g., in the catfish, described on page 263, in which the 
Ovaries weighed 2003 grains, the ova contained in them would, when fully 
* As a general rule, but not invariably, the upper ovary in a flatfish is longer and 
heavier than the lower. For convenience, when distinguishing the ovaries in flat- 
fish, I have used the terms dorsal or ventral ovary to mean the superior or inferior 
ovary when the fish is in its natural position, irrespective of anatomical considerations. 
