CHAP. XXVI.] VIEW FROM LIGHTHOUSE. 85 



other trees just beginning to put forth their young leaves. As the 

 most northern countries I had visited in Europe Norway and 

 Sweden were characterized by fir trees mingled with birch, I 

 was surprised to find the most southern spot I had yet seen, a 

 plain only a few feet above the level of the sea, almost equally 

 characterized by a predominance of pines. On the ground I ob 

 served a species of cactus, about one foot high, and the marshy 

 spots were covered with the candleberry (My-rica carolinensis), 

 resembling the species so common in the north, in the scent of 

 its aromatic leaves, but thrice as high as I had seen it before. 

 The most common plant in flower was the English chickweed 

 (Cerastium vulgare), a truly cosmopolite species. 



A prodigious quantity of drift timber, of all sizes, and in every 

 stage of decomposition, lay stranded far and wide along the shore. 

 Many of the trunks of the trees had been floated a thousand miles 

 and more down the Mississippi and its tributaries, and, after escaping 

 by one of the many mouths of the great river, had drifted one hun 

 dred and fifty miles eastward to this spot. The fact of their long 

 immersion in salt water was sometimes proved by a dense coat of 

 encrusting barnacles, the only marine shells we could find here, 

 for the mollusks proper to this part of the bay are such as belong 

 to fresh or brackish water, of the genera Cyrena, Gnathodon, and 

 Neritina. Just before our visit, a north wind had been blowing 

 and driving back the sea water for some days, and the bay was 

 so freshened by the Alabama River pouring in at this season a full 

 stream, that I could detect no brackish taste in the water. It 

 is, in fact, so sweet here, that ships often resort to the spot to 

 take in water. Yet there is a regular tide rising three feet every 

 six hours, and, when the wind blows from the south, the waters 

 are raised six or seven feet. 



After walking over a large expanse of ripple-marked sands, we 

 came to banks of mud, inhabited by the bivalve shell called 

 Gnathodon, some of which we dug up alive from a depth of 

 about two inches from the surface. This part of the bay of Mobile 

 is now the most northern locality of this remarkable brackish-water 

 genus, but dead shells of the same species are traced many miles 

 inland, forming banks three or four feet thick. They are called 



