MACKERELS, HORSE-MACKERELS, ALLIED FORMS 135 



a continuous fishery of the kind would not tend to exhaustion, 

 is another question. 



It is the business of the biologist to ascertain these facts ; 

 it is then the business of the legislator to act upon them. 

 Certainly the problem is one that should fascinate all with 

 opportunities for studying it. The presence of mackerel in 

 the trawl, as well as in the stomachs of the cod and other 

 ground-feeding fishes, points to a retreat to deep water in the 

 winter, and this may perhaps be undertaken to avoid the 

 extreme cold of the shallows during the months in which the 

 sun is giving its greatest heat to the mackerel of Australian 

 seas. The difficulty may eventually be solved by the deep- 

 sea thermometer, which will show us the depth and distance 

 from land at which the mackerel would be most likely to 

 find a congenial winter residence. Little by little science is 

 substituting fact for fiction. We have grown out of the simple 

 faith that accepted stories of mackerel hibernating with their 

 heads buried in Arctic mud, and we find, on comparing the 

 two, that the truths of nature are quite as wonderful as the 

 fables of man. 



The Spanish Mackerel (S. colias) is a much rarer and also 

 less important fish in our seas, being in fact only a wanderer 

 from the Mediterranean. It resembles the ordinary mackerel 

 in colour, but is distinctively marked with blotches and spots, 

 and the eye is conspicuously larger. It has, moreover, an air- 

 bladder, which the common mackerel lacks, and it shows 

 rudimentary traces of a corselet of scales, which is more 

 highly developed in the bonitoes. Its flesh becomes unfit for 

 market after capture even more rapidly than that of the 

 common species, so that commercially it is of no account. 

 Still, it is a beautiful fish, and Dr. Bashford Dean * takes it as 

 the type of a fast-swimming fish, with its rounded surface, 

 tapering spindle outline, smoothly closed gill-covers — in short, 

 as seen from the front, a small but perfect ellipse. The 

 * Fishes, Living and Fossil, p. 3. 



