24 THE CANADIAN NATURALIST. [Vol. vii. 



by the Trinidad mountains to the eastward, and does not appear 

 on the lower part of the Damuji, where an older series comes to 

 the surface. 



The surface deposits both on this river and at Cienfuegos 

 are of much interest, and especially the estuary-flats along the 

 river itself. These flats exhibit the action of an ao-encv which 

 has played an importint part in influencing the accumulation of 

 estuary deposits in tropical regions. In approaching the outlet 

 of the Damuji no break in the long green bank of foliage at the 

 head of Xagua Bay enables one to divine where the river's mouth 

 may be, but the entrance to the stream is betrayed by the flocks 

 of pelicans and other natatory birds which seek their food on 

 tlie Ion"; submerged bar extending out from the entrance. Even 

 within the narrow opening, in what appears to be a broad tree- 

 covered flat submerged bv rising waters, there is not for several 

 miles any visible bank to the river, but the waters spread out 

 freely over the mud-flats upon which the mangroves grow. These 

 trees by their great stools of roots and by numerous descending 

 branches which root in the mud, interpose a strong check to the. 

 outward rush of the water when the stream is in flood, and 

 cause it to deposit a great part of its sediment before reaching 

 the seas. The mud-banks along that part of the Damuji upon 

 wliich the mangroves grow are of a yellowish-brown or grey 

 color, and contain shells of a small species of oyster, a mussel, 

 a fresh-water cerite (JJerithidiu7ii), and a small conical univalve 

 (^Melampus.) These shells and the smaller organisms entombed 

 in the silt, would add greatly to the fertility of soils derived 

 from the mud-flats, if, through the action of disturbing forces 

 in the earth's crust, they become elevated above the sea-level. 

 Such alluvial tracts exist in the valley of the Damuji, and the 

 indications elsewhere of recent changes in the level of the land 

 render it probable that they exist in most of the river valleys of 

 Cuba. A short distance above the Ferry, where the main -road 

 from Cienfuegos crosses the Damuji, an extensive flat occurs, 

 elevated about ten feet above the river ; and at about the same 

 level, near the town of Cienfuegos, there are surface deposits con- 

 taining marine organisms. These bed rest upon clays, which con- 

 form to the inequalities of the upturned and eroded Miocene 

 strata, and are found at difl"erent heights, from the present sea 

 level to fifteen feet above it. They cover the bottom and sides of 

 a shallow depression in the land through which a small brook runs 



