44 



BULLE'I'IX OF THE NATURAL HISTORY SOCIETY. 



middle of tlie base to the apex. Their extreme points 

 are very low and muddy and sink gradually under water 

 to continue as shallows still farther out, but in one place 

 they come to the surface again as a small marshy island, 

 which, perhaps, marks the beginning of the splitting of 



g Giova 

 :•• niuA 



Scute 



/ooyards 



Fi G. 



Sketch map of the Delta. Depths from the 1797 survey map. Only the 

 southern point was studied ; the dotted line shows the probable outline 

 of the northern point. The map is a mere sketch to illustrate points in 

 the paper and topographically must be very inaccurate. 



the channel into two. The characteristic grass of the 

 shallows is Glyceria fiuitans R. Br. Farther in the land 

 rises very gradually, the mud becomes iirmer and bears a 

 great deal of the small sedge. Eleocliaris tenuis, Sc/ndtes. 

 Here the bank is very steep on the canal side, near which 



