ON EESEARCHES ON FOOD-FISHES AND INVERTEBRATES. 269* 



tion of a few unimpregnated ova observed during the trawling experi- 

 ment^ of 1884, the earlier stages have yet to be examined. The large size 

 of the embryos of the catfish permitted a satisfactory comparison to be 

 instituted between them and the salmon, which had formerly been under 

 examination, and the results, with drawings of both forms, are nearly 

 completed, and will be communicated to one of the Societies during the 

 winter. 



The first pelagic ova, viz., those of the haddock, made their appearance 

 during the very cold weather in the beginning of February, and the exa. 

 mination of these, together with those of the cod and common flounder — 

 both of which were unusually late — enabled Mr. E. E. Prince and the 

 Secretary to extend considerably the observations of last year. Moreover,. 

 for the first time, the ova of the ling (Molva vulgaris) were examined, 

 and the development followed to a fairly advanced stage. These were 

 procured by a long-line fisherman of Cellardyke (who with others 

 was supplied with suitable earthenware jars' and encouraged by a visit 

 to the Laboratory), fertilised about 100 miles ofiF the Island of May, and 

 safely brought, after a considerable land-journey, to St. Andrews. The 

 fertilised ova of the plaice and lemon-dab were similarly brought by 

 Captain Burn, late of the Hussars, from the Moray Frith ; for the Labora- 

 tory had then no boat suited for procuring a supply nearer home. No 

 fish, however, has been moi'e useful to the workers this season than the- 

 gurnard {Trigla gurnardus), the spawning period of which seems to have 

 been somewhat later than usual. The first ova were procured about the 

 middle of May, and the embryos of the last hatching (middle of August) 

 still swarm in the vessels. Further observations were also made on the 

 ova and young of the lumpsucker, Montagu's sucker, shanny, stickleback, 

 sand-eel, Coitus, &c. Amongst others the nearly ripe ovum of Ainmodytes 

 tdbianus has been examined. It is colourless, translucent, and has a 

 beautifully reticulated capsule. Mr. Prince is of opinion that, as sug- 

 gested in the ' Report of H.M. Trawling Commission,' it resembles a 

 pelagic e^g. 



Moreover, the information necessary for filling up the gaps between 

 the very early stages of the young food-fishes near the surface and their 

 appearance off" the shore as shoals of young forms more or less easily 

 recognisable specifically has been considerably increased. Much of this 

 knowledge has been obtained by the aid of a huge tow-net of coarse 

 gauze — upwards of twenty feet in length — attached to a triangle of wood, 

 ten feet each way, sunk by a heavy weight and kept steadily at the 

 required depth in fathoms by a galvanised iron float, such as is used for 

 the ends of herring-nets. Since the completion of the net, however, 

 the services of the Fishery Board tender Garland have only once been 

 available, and the yawl has been at our disposal only a few weeks. In 

 these brief opportunities, however, the young of various fishes have been 

 obtained at stages hitherto unknown, and some rare invertebrates and a 

 remarkable Medusa have been captured. Enough, in short, has been seen 

 to indicate the value of this apparatus, and of certain modifications of the 

 ordinary beam-trawl for work on the bottom. 



The hatching and rearing of the embryos of the common food-fishes 

 have been attended with much greater success than last year or the 



> Containing about a gallon. These were partially filled with pure sea-water 

 then containing fertilised ova, and simply tied over with porous cheese-cloth. 



