40 



PLATE XL 



GUAHAM, ONE OF THE MARIANNE ISLANDS. 



FOREST IN THE PLAINS OF MADREPORE, OROTA PENINSULA. 



March. 



As far as the Mariannes are represented by Gruaham, the most extensive and 

 southernmost of these islands, they are at once distinguished from the more 

 northern Caroline group by their dry climate, which imparts to the whole country 

 the look of a steppe. The month of March, in which our visit fell, is evidently 

 the dry season of these regions ; everywhere is aridity, very few trees with fresh 

 foliage are seen in the forest, and perhaps the third part of all is quite leaf- 

 less. The sea-shores are either kept supplied with moisture by rivulets from the 

 interior, and then overgrown with Bruigiera and other mangroves, or they are 

 sandy, and in the latter case distinguished by two forms very characteristic of 



shrubby pyramidal Casuarina*, which is again met with in the upper steppes of 

 the interior, though wanting in the intermediate forest district. Banks of coral 

 surround the shores on all sides, making this larger island, as the high Carolines, 

 appear like mountains risen in the centre of extensive coral plains. Here and 

 there considerable districts of these plains have been lifted by plutonic agency 

 high above the sea level ; the Orota peninsula, confining the south-west side of 

 the bay of Caldero de Apra, is one of these. The low, sandy shores are evidently 

 later diluvial deposits ; a few steps from the water's edge the walls of very ancient 

 madrepore rocks rise perpendicularly, the surface of which is as level as most coral 

 islands, and they only seem sloping by the accumulation of vegetable mould. 

 This plain, which, as may be supposed, is utterly destitute of springs, is never- 

 theless covered with fine tall trees, and, although thorny underwood abounds, is 



this island, — Cycas revoluta 



common hereabouts, and a 



* Probably Casuarina equiseiifolia, Forst. — Berthold Seemann. 



