TRAWLING. 47 



of fish, of almost every kind which they are accus- 

 tomed to catch, having certain grounds which they 

 frequent at particular seasons for the purpose of 

 depositing their ova. Yet it will hardly be credited 

 that the herring is the only one of those fish whose 

 spawn has ever been found on the ground. And the 

 evidence on this point is by no means only of a nega- 

 tive character. During the last ten years Professor 

 G. O. Sars, under the direction of the Swedish Govern- 

 ment, has been investigating the subject of fish-spawn- 

 ing, and has obtained the most positive evidence of 

 the ova of several of our best-known fish floating at 

 the surface during the whole period of their develop- 

 ment. Among those whose ova have been found float- 

 ing, and have been successfully hatched out, and the 

 young fish identified beyond a doubt, are the cod and 

 haddock. If such be the case with these two species 

 of the same genus, there is hardly room to doubt that 

 the very closely allied species, such as the whiting, 

 coalfish, pollack, hake, and tusk, have precisely the 

 same habit of spawning at the surface. The spawning 

 of the mackerel at the surface has been repeatedly 

 seen, and the floating ova have been collected in all 

 stages of development, and thoroughly identified. 

 Still more surprising is the fact, that Professor Sars 

 and M. Malm have independently discovered on 

 different parts of the Norwegian coast, that the com- 

 mon plaice, regarded by naturalists as the typical 

 representative of the family Pleuronectidoe, which in- 

 cludes all our various kinds of flat fish, has precisely 

 the same habit of spawning at or near the surface, and 



