of the Fishery Board for Scotland. 



285 



thousauds caught off Shetland, and which was distended with the usual 

 crustacean food, no less than thirty entire pelagic eggs of various species 

 of fishes were found. It is true that these had in all probability been 

 swallowed as the fish gulped the swarms of swimming crustaceans, yet the 

 loss from this cause alone must be serious. It is rare, however, to find 

 pelagic ova in the stomachs of marine animals, yet on one occasion ducks 

 and other birds were feeding on these and perhaps the larval fishes in the 

 Moray Firth ; and Captain Dannevig has observed sprats snapping at the 

 pelagic eggs as they escaped from a breeding pond at Arendal. At no 

 period, indeed, during the life-history of the food-fish is it free from attack. 



The enormous quantity of pelagic fish-food poured by the neighbouring 

 mussel-beds into the inshore waters has often been referred to in communi- 

 cations from the St Andrews Marine Laboratory. It is one of the most 

 constant factors in the annual supply — first, as minute ciliated spheres, 

 then almost as minute swimming mussels in June, which crowd the waters 

 both at the surface and the bottom, and afterwards settle down like grains 

 of millet-seed on zoophytes, sea- weeds, stones, shells, and indeed on every 

 available site, such as the ropes, buoys, and other parts of the salmon 

 stake-nets.* But while the foregoing mollusks are perhaps the most 

 conspicuous forms in their season, they are not by any means the 

 only ones, for both bivalve and univalve shell-fishes in their early 

 stages are common in the nets throughout the greater part of the 

 year, some of them, e.g., the peculiar flattened spiral shell of the young 

 Lamellaria, being so unlike the adult (a more or less sedentary form 

 amongst the rocks) as to have misled zoologists as to its actual position, 

 which was, however, clearly defined, amongst others, by Prof. A. Giard 

 of Paris,! a distinguished naturalist, who has largely extended our know- 

 ledge of marine animals. The foregoing forms, with occasional additions 

 of Spirialis- and Clione, take the place of the abundant and varied 

 Pteropods, the curious Glaucus, and the brightly-coloured Ianthina of 

 the warmer seas. 



The remarks made some years ago concerning the distribution of the 

 Appendiculaiians have been borne out by further experience, the immense 

 multitudes of Oikopleura cophocerca, Gegenbaur, and their houses, being 

 characteristic of April and May. The specimens are remarkably fine — 

 according to Prof. Herdman, quite as large as those procured during the 

 voyage of the ' Challenger.' The influence of such forms upon marine 

 life of all kinds must be considerable. The profusion of Actinotrocha, 

 the larval form of Phoronis, is one of the most diagnostic features of 

 August, though early specimens appear in June, and many in July and 

 September. 



No group of pelagic marine animals is more generally distributed 

 throughout the water than the Crustaceans, especially the countless 

 swarms of the Copepods, though certain Amphipods and Thysanopods also 

 occur in great numbers, and form rich feeding-grounds for many fishes, 

 the nets in such areas being rapidly filled with a semi-solid mass of their 

 bodies. The vast numbers of the larval sea-acorns, again, in spring is a 

 noteworthy feature in the inshore waters, where rocks, wood — both sta- 

 tionary and floating — and every available surface, is coated by a densely 

 grouped series as they become sessile. Some fishes, e.g., Gobius, in the 

 estuary of the Eden, feed largely in May on the C#pm-stage of these 

 sea-acorns. No Amphipod, again, appears to be a more conspicuous 

 feature in the pelagic fauna than Paratkemisto, which characterises the 

 winter months, especially January and February. 



* The salmon fishermen observe that the ropes have been submerged a month (viz. , 

 from May till the middle of June) before a deposit of the minute mussels is noticed, 

 t Comptes Rendus de VAcad. des Sc., 22 Mars 1875. 



s 2 



