ON ASCIDIANS AND FOOD-FISHES. 21 



It would appear, therefore, that for ages the inhabitants of 

 the sea have largely used the cuttlefishes as food, and to some 

 extent man, both as food and bait, yet these active and 

 generally pelagic forms have not been extirpated. The com- 

 mon species seem to be as abundant as formerly, though their 

 appearance is at all times uncertain. They occur, like so many 

 oceanic forms, suddenly in great numbers on certain grounds, 

 destroying the fishes on the hooks and boldly rising to the 

 surface after their prey as it is drawn up by the fishermen. 

 They also occasionally seriously interfere with the success of 

 the herring fishing (as in 1897) by appearing in great numbers 

 — to the injury of both fishes and nets. In the deeper 

 waters of the Pacific as well as in the other great seas they are 

 abundant, notwithstanding the constant warfare of whales and 

 fishes. This is probably due, as already indicated, as much to 

 the vastness of the area of their distribution, the depths which 

 they frequent, and the provision of the inky cloud, as to the 

 protection of the eggs in tough capsules, by a shell or by 

 enveloping mucus, and the pelagic young. A few, again, have 

 floating eggs, and thus the means for their increase are both 

 varied and extensive as well as beyond the influence of man. 



The group of the Urochordates offers few points for remark 

 — except that there is no sign of exhaustion in the common 

 forms within tide-marks and beyond it. The enormous num- 

 bers of the pelagic appendicularians and their gelatinous houses 

 is one of the features of the ocean, which in certain places is 

 discoloured by them. Moreover, they feed on microscopic 

 plants, while the smaller fishes and other forms prey on them. 

 The cycle between oceanic plants and fishes has therefore more 

 than one illustration. In this and allied groups the larval form 

 is often more conspicuous than the adult, thus the larva of 

 Phoro7iis abounds in St Andrews Bay from July to September, 

 yet the adult has never been found within it. 



We now come to the consideration of by far the most im- 

 portant group in relation to man, viz., the food-fishes of the sea. 

 These comprise the ordinary round fishes, such as the cod and 

 the herring, the various kinds of flat fishes, the skate (belonging 

 to the cartilaginous fishes), and a few others. For ages these 



