oj tfie Fishery Board for Scotland. 
245 
having pelagic ova, and probably indicates a number of successive ex- 
trusions of ova at short intervals. On the other hand, in Coitus scor- 
jrius and Agonus catuphradas the ova were of uniform size, none 
minute being present ; but only one mature specimen of each of these 
species was available, the others — at least of Coitus scorpius — being spent, 
and the ova in them probably represented the last crop. Anderson Smith 
has described the deposition of the ova of Liparis and Lepadogaster* 
The same observer has also found contiguous series of ova of Syngnaihus 
acus, apparently representing distinct depositions (vide below, p. 261) as 
with Gasierosieus. 
Agaiil, among all fish with isolated pelagic ova, the extrusion of the 
ova never takes place at once, but after successive intervals, extending 
over a period, the duration of which seems to vary very considerably in 
different species. It will be seen below that in some forms the great 
majority of the ova undergo practically equal and uniform development 
up to a certain point, as in the saithe, tusk, ling, cod, turbot, halibut, 
plaice, craig-fluke, flounder, and long rough dab. It will be observed 
that most of these are large iish. But, among others, the ova are of very 
different sizes, graduating down to microscopic, even after spawning has 
begun and continued for some time, e.g., lemon sole, common dab, mackerel, 
haddock, and especially the whiting and gurnard. In the latter group 
(comprising smaller fish) there does not appear to be space for all the 
ova necessary, even when they are but moderately developed, and the 
spawning process is no doubt prolonged.! 
For these reasons it is obvious that, except in a very few cases, it is not 
possible on such data alone to give accurately the ratio between the weight 
of the body and the reproductive substance produced by a single individual. 
Nevertheless, it is possible to show that considerable differences exist in 
different species, and a few examples from the tables I have prepared are 
given in the following tables, which show the ratio of ike weight of the 
ova present at one time to the weight of the rest of the fish taken at 1000 : — 
1. Fish with Demersal Ova. 
Species. 
Number 
Examined. 
Minimum 
Ratio. 
Maximum 
Ratio. 
Lumpsucker, 
Cottus hubalis, . 
, , scorpius, 
Liparis montagui, 
Sparling, 
Sand-eel, 
Herring, 
3 
4 
1 
1 
1 
2 
3 
16 
223-01 
109-93 
205-67 
67-99 
152-39 
348-33 
253-94 
309-78 
122-86 
345-16 
* Notes on the sucker fishes, Liparis and Lepadogaster, Proc. Hoy. Phys. Soc, 1885. 
+ In the angler, where the ova are pelagic but united together, extrusion probably 
takes place with some rapidity ; impregnation being assured by the great excess of 
males. In a female Lophius w\i\qX\ I opened in January on board the 'Garland,* 
the long flattened ovaries, about 20 feet in length, were coiled up in the abdominal 
cavity, and exhibited worm-like or gliding movements. The ovary forms a wide, 
flattened, thin-walled tube, the ova being arranged in a layer in the form of a band 
occupying half the circumference of the tube. 
