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were Avicennia and Laguncularia, but even these species seem 

 gradually to be obliged to retire from these localities, often quite 

 devoid of any vegetation whatever, or only inhabited by some 

 smaller marsh shrubs. 



However, it is not always that the development takes this 

 course; often the heaping up of the deposits takes place more 

 evenly over the whole region, and when the ground is simultaneously 



Fig. 7. J.«;icenma-association at the head of Christianssted's Lagoon, St. Croix. 

 Numerous pneumatophores are seen rising from the mud. (F. B. phot.) 



rising, the result will be a low-lying flat dry land ; and on this 

 land the mangrove vegetation seems to thrive better. As already 

 mentioned very vigorous RMzopJiora-^ovesis are to be found on a 

 quite dry soil, e. g. the above mentioned one in Great Gruzbay on 

 St. Jan, of which the accompagnying picture (Fig. 6) gives a view 

 of the interior. But no doubt it is Avicennia and especially 

 Laguncularia which are most adapted to these habitats. 



At the head of Ghristianssted's lagoon, where almost dry 

 stretches are found, a luxuriant Avice}inia4ove?,i (fig. 7) is present 



