DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 669 
Pexacic Ova. 
General Remarks.—The pelagic nature of the ova of so large a number of valuable 
food-fishes removes them altogether from many of the vicissitudes which befall demersal 
egos, Their transparent glassy nature, minute size, and enormous abundance, sufficiently 
provide for their safety and the increase of the species. Pelagic ova are by no means 
common in the stomachs of fishes, while ova deposited on the bottom (e.g., those of 
Cyclopterus, Cottus, and Clupea harengus) are eaten by many fishes with great avidity, 
yet the numbers of one of these at least are, so far as can be made out, by no means 
seriously affected. How much more surely, then, is the multiplication of those with 
pelagic ova provided for? As a rule, they are deep enough to escape the vicissitudes of 
the immediate surface, and in our country are seldom stranded on the beach in numbers 
sufficient to attract attention.* The larvee which escape from them are also minute and 
translucent, and thus are less prone to attract the notice of predatory marine forms ; more- 
over, they soon become very active, while their purely pelagic life gives them a vast area 
for their safe development. 
The contrast between such types and the condition, for instance, in Cottus, is marked. 
In the latter the ova are deposited between tide-marks in masses, and are often devoured 
by other fishes, and it may be by predatory birds and mollusks. The comparatively large 
young are conspicuous objects, and can only escape by keeping within reach of tangles 
and other sea-weeds, a constant reduction of their numbers taking place, notwithstanding 
their defensive armature, during the somewhat slow growth to the adult condition. It is 
possible, indeed, that though the egg-capsules in Cottws are much denser, and the embryos 
larger and more highly developed than in the cod, a much greater number of the latter 
proportionally reach maturity than in the case of the former. 
On the eastern shores pelagic ova begin to appear at the end of February, though 
there is no reason why some should not be found earlier, as Dr J. Murray tells us they 
are on the west coast (Clyde district), and a kind of succession of those of different species 
oceurs throughout the spring, summer, and autumn. Amongst the earliest are the ova 
of the plaice, Wotella, and the large egg with the spacious perivitelline space, the larval 
form issuing from which is described subsequently. Those of the Gadoids, such as the cod, 
haddock, and whiting, next appear, and also those of the flounder and dab, while towards 
the end of the month the eggs of the gurnard are also captured. April is characterised 
by the abundance of pelagic ova, the maximum perhaps being attained towards the latter 
part of the month, when the ova of the spratt and other forms swell the list. As an 
at times noticed the little transparent globular bodies in the water; but it never occurred to them that they were the 
eggs of any fish. They may be found at the surface in common with the eggs of pollack, haddock, and probably other 
species of the cod family, when the sea is smooth, but when the water becomes rough they are carried to a depth of 
several fathoms by the current, though the tendency is to remain near the surface” (No. 8, p. 715). 
* G. O. Sars found, however, that they were so at Lofoten. 
+ HeEnseN first noticed the pelagic ova of the sprat, and his observation has been corroborated by J. T. Cunnino- 
HAM and ourselves. Other Clupeoids, as shown by RaFFaxg xe, also have pelagic eggs. 
