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Part III. — Eleventh Annual Report 



VIII.— THE PELAGIC FAUNA OF THE BAY OF ST ANDREWS. 

 By Prof. M'Intosh, M.D., LL.D., F.R.S. 



The pelagic fauna of the bay, while presenting certain common features 

 in the monthly returns from year to year, yet often shows considerable 

 variations. Thus, for instance, the beautiful and conspicuous pteropod 

 Clione, which appeared in April ] 887, was not again met with till the 

 spring of this year (1893). Tl^ abundant ctenophore, PleurobracJiia, 

 which had been one of the most constant and most plentiful of the pelagic 

 medusae, completely vanished for the first nine months of 1891 — to the 

 disappointment of Mr Riches who, on the faith of its well-known frequency 

 in our nets, had specially come from Plymouth to study its development 

 and life-history. No sooner had he returned southward than it again 

 appeared, and has been constantly met with since. It would be difficult 

 to explain the cause of so sudden and so complete a disappearance. 

 During no season have the myriads of larval and post-larval herrings so 

 rilled the bay as in the spring of 1889, when it became necessary to cease 

 to use the bottom trawl-like tow-net, which captured them in immense 

 multitudes. These larval herrings had probably been carried into the bay 

 by currents from the mouth of the Forth, since, so far as known, no depo- 

 sition of ova takes place in the bay itself. It is, indeed, many years since 

 the eggs of the herring have been noticed at the Old Hake, off the east of 

 Fife (near the Carr Lightship), where Lord Playfair and Prof. Allman 

 carefully investigated them. At any rate, whether eggs are deposited 

 within or near the bay, there is no lack of larval herrings under ordinary 

 circumstances, and the same may be said of sprats. 



The young of certain fishes not usually encountered in the pelagic 

 fauna occur at certain definite seasons. Thus the young great pipe-fishes 

 are common in the bottom-nets off the estuary of the Eden. On the 

 other hand, the young eels bury themselves in the sand. The larval fish 

 E (Seventh Annual Report, III., pp. 263 and 309, Plate III. figs. 5, 6, 

 and 7) has again been encountered off Tents Moor, but no further light 

 has been thrown on its relationship, though in some respects it approaches 

 Cottus. 



If the weather in the first part of May be warm, the young Pleuronectids 

 (such as plaice, dabs, and flounders) of the season often disport themselves 

 at the surface of the water, and can be caught with a hand-net in consider- 

 able numbers. This feature was formerly noticed chiefly in the turbot 

 and brill later in the season, e.g., in July and August. On the other hand, 

 the scanty numbers of post-larval gadoids afforded a contrast to the waters 

 of Smith Bank in the Moray Firth, where the post-larval gadoids, ranging 

 from 4 to 16 mm., disport themselves, at the end of April and beginning 

 of May, in multitudes, chiefly near the bottom, though also at the surface. 



It is generally supposed that the transparent eggs of the food-fishes, which 

 form one of the most important elements of the pelagic fauna, escape many 

 dangers from their invisibility. It has to be remembered, however, that 

 the embryos in these eggs are sometimes conspicuously coloured with 

 black and yellow — just as the supposed inconspicuous medusae are with 

 blue, orange, brown, red, and black, though of course the full develop- 

 ment of the pigment in the fish only occurs a short time before hatching. 

 Some embryos remain almost devoid of pigment before extrusion — as the 

 sprat, and an unknown form sent to Mr Holt from the west coast of 

 Ireland. An important fact in this connection has also been observed, 

 viz., that in the stomach of a single herring taken from the midst of 



