27 



the exception of a few in the north-eastern section of 

 the lagoon which are served from a small canal called 

 Bocca del Bianco, a natural sea-channel through the 

 Lido, scarcely 12 metres wide, not always active, and 

 serving directly two valli only. 



The channel of Magnavacca after traversing the 

 Lido bifurcates ; each branch almost at once begins 

 to give off ramifying side branches at varying intervals 

 each having the same breadth as the mother channel. 

 Each of these subsidiary branches eventually divides 

 into a fan of terminal channels opening into one or 

 other of the several valli. Two of the main canals are 

 of special importance — those which diverging from 

 Magnavacca in the form of an immense V penetrate 

 ultimately to the Mezzano Valle and are the only means 

 of communication between this vast sheet of water and 

 the sea. These two canals serve roughly to separate 

 the eastern half of the lagoon into three divisions, a 

 southern section of three principal valli, aggregating 

 6,548 hectares (16,181 acres), a northern set of valli with 

 a superficies of 8,539 hectares (19,989 acres) and a 

 median division embraced between the arms of the V 

 with an area of 4,302 hectares (9,631 acres). 



The Mezzano owing to the enormous area it covers 

 is the most important fish-farm in the lagoon, being 75 

 kilometres (46^ miles) in circumference, 14 kilometres (8f 

 miles) from north to south and 18 (about 10^ miles) from 

 east to west. Unfortunately it is the most remote of all 

 the valli from the sea, the shortest of the canals connect- 

 ing it with the Port of Magnavacca being 10 kilometres 

 long, while the southern sea-water sluices are as much 

 as 14 kilometres distant from the sea. 



Command of large supplies of river water is also as 

 vital a necessity as communication with the sea both 

 in order to reduce excessive salinity within the valli and 

 as an integral factor in the annual stocking of the valli 

 with new shoals of fry. To effect this, six sluices fur- 

 nish communication between the river Volano and those 

 valli which approach the right bank of this stream; in the 

 same way the lagoon communicates at intervals along its 

 southern border with the Reno by five similar sluices. 



The town of Comacchio lies at the present day in the 

 heart of the seaward half of the lagoon, upon a long 



