Tanks No. 10 and 16, 
85 
the rivers. In stormy weather it approaches the coast in large numbers 
to feed on the crabs which are carried away by the waves. It is generally 
caught with the line, large specimens offering very energetic resistance. 
In the Aquarium it lives for years and will spawn freely, but unfortunately 
the young have not 
been able to be 
reared. Allied is 
the also active Po¬ 
lyprion (tank 10). 
Perhaps the most 
common fishes in 
the Bay are the dif¬ 
ferent species of 
Grey Mull et,Mugil 
(Fig. 150). They _ 
are easily distinguished by their slender, silvery grey bodies, and their 
curious lips. The upper lip is provided with a notch into which fits a 
process of the lower lip. They swim round the coasts in shoals and live 
Fig. 153. Box salpa, V 2 nat. size. Tank 2. 
on soft decaying matter. In tank No. 16 they will be seen feeding on the 
sea-weeds and on decaying animal and vegetable products, so that they 
are distinctly useful animals. Their flesh is very good, and as they are 
very common, they form a staple article in the Italian markets (" Cefalo ”). 
We have further to mention a number of fishes, which are always 
