62 NATURAL HISTORY OF 



Zee, by breaking through the coast more to the north 

 than the ancient channel, which was a river then known 

 "by the name of Flevus, whose waters were discharged 

 close to the present Flie island. Another great sub- 

 mersion, in the south-east of Holland, was felt at the 

 Biesbosch, near Gertruydenberg, in 1421, when the 

 waters of the Meuse and Waal, suddenly overwhelming 

 seventy-two villages, 100,000 human beings were lost ; 

 but the subsoil must have sunk at the same time, since 

 the whole region has remained beneath the surface, and 

 is now overgrown with huge reeds. 



The principal mouth of the Rhine, during the Roman 

 sway, is all but obliterated, excepting in name, and 

 the whole coast of Holland has much receded from its 

 earlier tide mark ; for, at the spot where the Rhine 

 mouth entered the sea, there stood a fortress, by some 

 ascribed to Drusus, by others to Claudius, intended to 

 guard the entrance. The whole plan of this structure, 

 with walls of hewn stone, still three feet high when it 

 was last seen, is now buried under the waves, and more 

 than a mile from the present shore.* Coins of Postu- 

 mus, Yictorinus, and Tetricus, with others resembling 

 early Anglo Saxon Skeatta, indicate that the fortress 

 was garrisoned, and therefore, that the river was still 

 navigable after the Roman departure from Britain. 



* This place is known by the name of Huis-ten Britten. 

 Here several alto relievo figures of the goddess Nehalennia, 

 and many coins have been found during very low tides. 

 The ruins have not been seen above water during the last 

 hundred years. 



