470 A. EF. Verrill—The Bermuda Islands. 
6.—Mangrove Swamps. 
When small bays or lagoons are thus formed by the invasion of 
the sea, if they should be sheltered from violent waves, mangroves 
and black-jack trees take root in the sea water itself, as well as 
along its borders. By means of the peculiar descending shoots or 
aérial roots of the former and the ascending shoots from the roots of 
the latter, a dense thicket or mangrove swamp is soon formed, admir- 
ably adapted to collecting and retaining dead leaves, mud, and sedi- 
ment of all kinds, thus gradually increasing the area and fertility of 
the land. (See plates Ixviii, fig. 2, and ixxiv, fig. 1, and Native 
Trees, Part III, ch. 26, e.) 
Such mangrove swamps, usually of small extent, exist in many 
places, as at Coney Island, Walsingham, Spanish Point, Tucker’s 
Town, etc. Larger and denser ones may be seen at Hungry Bay, 
Mangrove Bay, and several other places. 
7.— Caverns and Grottoes. 
Among the more interesting ot the geological phenomena are the 
numerous caverns, usually hung with numerous huge stalactites, but 
sometimes with innumerable small and delicate ones ; and in some 
places decorated with the most delicate fret-work, or with thin, 
translucent draperies, of snow-white stalactitic material. 
Some of these caverns are of considerable extent, but the larger 
ones are generally partly submerged below the level of the sea, so 
that the floor may be covered with clear sea-water, 10 to 20 feet 
deep. Sometimes stalagmites can be seen rising up from the bot- 
tom, beneath the sea water. A large cavern on Tucker’s Island,* of 
this description, had been fitted with pipes for acetylene gas and the 
proprietor had a boat inside, with which he, like Charon, took’ his 
visitors across the dark and mysterious waters. In this cavern the 
stalactites are of colossal sizes, but they are dark and dull in color, 
as if finished ages ago, as indeed they doubtless were. 
On the Walsingham place there are several well known caverns. 
We succeeded in obtaining photographs of two of these. (See plates 
xe-xcil.) One of them has two entrances and does not contain water, 
though it is in a depression, not much above sea-level. It is near 
Thomas Moore’s famous Calabash Tree. The stalactites are of large 
size, but badly smoked by the torches and bonfires of the innumer- 
* Since my visit, this island has been converted into a prison-camp for the 
Boers, and is not at present accessible to the public. 
