- 236 — 



with undulated walls: the stomata lie in the same plane as the 

 surface of the epidermis. 



Round the vascular bundle a large sheath of sclerenchyma is 

 present and from this single sclerenchyma-cells escape and are to 

 be found round in the tissue of the leaf (cfr. a and d). 



Large crystals of oxalic chalk are also present. 



Long hairs occur scattered over the underside of the leaf. 



II. The sand strand vegetation. 



9 (Cfr. B0rgesen, 1898, p. 4; 1900, p 3.) 



This is found on open sandy coasts exposed to the wind and 

 naturally groups itself into the 3 formations : 



L The Fes caprce formation growing outermost nearest the 

 sea on the freshest soil and consisting particularly of herbaceous plants. 



2. The Tournefortia formation right inside on somewhat more 

 elevated and older soil consisting of bushes, and lastly innermost 



3. The Cocco/o6rt-Manchineel formation growing on the oldest 

 most elevated ground and consisting of larger bushes and trees, 

 which may develop into a regular forest. 



As already mentioned in my earlier paper, the sand of the 

 West Indian coasts is commonly so coarse-grained that it cannot 

 be carried by the wind. It mainly consists of chalk-gravel, partly 

 and especially of coral-chalk but also several calcareous algae, 

 especially Halimeda but Corallina, Penicillus, Udotea, Litho- 

 thamnion and others greatly contribute to it, sometimes as already 

 mentioned above, the sand almost entirely consists of remains from 

 the algse. That this course-grained sand is too heavy for trans- 

 port by the wind is quite natural, and proper dunes are thus not 

 found on our islands, but in some localities finer sand is to be 

 found, and where this is the case, e. g. on the north-west side of 

 St. Croix at the plantation "Northside", I have found a certainly 

 very small beginning of a formation of dunes (fig. 24). The 

 sand was here comparatively fine ^). Sheltered by stones and rocks 

 quite low mounds of sand were heaped up, on which several plants 

 of the Pes caprce formation especially Sesuvium portulacastrum L. 



M Docent Boggild has most kindly told me that it consisted of 93«lo chalk- 

 grains, 6 0|o slate and 1 "lo (juartz. 



