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Part III. — Seventh Annual Report 



The mid-water net was of service in regard to the post-larval fishes, 

 since no other known form of net has been so successful in capturing 

 these active forms. Lately, moreover, a net of a different kind has 

 been of great use in examining the bottom-fauna, viz., one constructed 

 after the manner of a small trawl. Thus the trawl-heads are of very 

 light iron, the beam a slender bar of elm, 8 feet 6 inches long; the net 

 (18 feet long) is in the form of a trawl-net, but composed of cheese-cloth, 

 with a terminal region 3 feet in length of ordinary (fine) cotton cloth. 

 The mouth of the net is kept about 9 inches from the ground by being- 

 drawn ' taut ' between the trawl-heads, and has an oblique aperture of 3 

 feet from beam to foot-rope. This is a most fatal net for larval fishes 

 and the swarms of invertebrates that haunt the bottom-water in early 

 spring, and should be used only for a short time. The mathematical 

 apportionment of the animals comprising the pelagic fauna therefore falls 

 short of the German method, but for all practical purposes connected 

 with the fisheries the plan here adopted is fairly satisfactory. It gives 

 at a glance the vast resources to be found in the sea for the nourishment 

 of the food-fishes, — resources ranging over the vegetable as well as the 

 animal kingdom, and comprehending under the latter representatives of 

 every class from the fishes downward. The importance of the pelagic 

 fauna in supplying food for fishes cannot be overestimated, for though 

 the adults of many of the food-fishes might obtain nourishment from the 

 bottom-fauna alone, it is certain that their post-larval and young stages 

 could not. Moreover, the remarkable adaptation whereby the most 

 minute post-larval forms, such as the very young cod, find in the pelagic 

 forms those that are suited for their wants is a striking feature. Again, 

 the terminal portion of the intestine in the larval herrings captured in 

 March shows a deep greenish coloration, which may be connected with 

 chlorophyll. Moreover, even so minute a form as an Infusorian is occa- 

 sionally in the larger fishes swallowed in masses as food. 



There is no more interesting point in the inquiry than the gradual 

 advent in the early part of the year of the larval fishes, and their great 

 abundance in the spring months, such as March, April, and May. Then, 

 while the larval stages of a few still appear in the warmer months, viz., 

 June, July, and August, the predominance of post-larval types of food- 

 fishes is the main feature. These become rarer in the pelagic fauna as 

 winter approaches, and finally almost disappear from the area in 

 question. 



In the same way the larval stages of mussels and other shell-fishes of 

 importance make their appearance at a stated period, continue in great 

 profusion for some time, and then gradually diminish and disappear. In 

 the case of the mussel the advent of the larval forms in swarms in the 

 bay is in touch with the ripe condition of the adult forms in the Eden 

 some time previously, the long-continued presence of certain of these 

 larvie being connected with the later maturation of the reproductive 

 elements in the littoral and often stunted examples so abundant in many 

 parts of the bay — especially amongst the rocks. 



Besides the special interest of the inquiry in connection with the 

 Fisheries, the bearing of many of the facts, e.g., the appearance and 

 disappearance of the multitudes of Medusae and Hydromedusse, are of a 

 novel kind, since even the most recent and most authoritative investi- 

 gators on the subject, such as Prof. Haeckel, do not give information on 

 this question. Little indeed has been done in this respect since the days 

 of Ed. Forbes, with the exception of the notes lately made at the Naples 

 Zoological Station. 



The pelagic fauna round the British shores seems to have many 



