saline shrub; its leaves have a salt taste; and it luxuriates in saline soils, where it is usually a characteristic. It is widely diffused over all this country. A chenopodiaceous shrub, which is a new species of OBIONE, (O. rigida, _Torr. and Frem_.,) was equally characteristic of the lower parts of the island. These two are the striking plants on the island, and belong to a class of plants which form a prominent feature in the vegetation of this country. On the lower parts of the island, also, a prickly pear of very large size was frequent. On the shore, near the water, was a woolly species of _phaca_; and a new species of umbelliferous plant (_leptotaemia_) was scattered about in very considerable abundance. These constituted all the vegetation that now appeared upon the island. I accidentally left on the summit the brass cover to the object end of my spy-glass: and as it will probably remain there undisturbed by Indians, it will furnish matter of speculation to some future traveler. In our excursions about the island, we did not meet with any kind of animal; a magpie, and another larger bird, probably attracted by the smoke of our fire, paid us a visit from the shore, and were the only living things seen during our stay. The rock constituting the cliffs along the shore, where we were encamped, is a talcous rock, or steatite, with brown spar. At sunset, the temperature was 70 deg. We had arrived just in time to obtain a meridian altitude of the sun, and other observations were obtained this evening, which placed our camp in latitude 41 deg. 10' 42", and longitude 112 deg. 21' 05" from Greenwich. From a discussion of the barometrical observations made during our stay on the shores of the lake, we have adopted 4,200 feet for its elevation above the Gulf of Mexico. In the first disappointment we felt from the dissipation of our dream of the fertile islands, I called this _Disappointment island_. Out of the drift-wood, we made ourselves pleasant little lodges, open to the water; and, after having kindled large fires to excite the wonder of any straggling savage on the lake shores, lay down, for the first time in a long journey, in perfect security; no one thinking about his arms. The evening was extremely bright and pleasant; but the wind rose during the night, and the waves began to break heavily on the shore, making our island tremble. I had not expected in our inland journey to hear the roar of an ocean surf; and the strangeness of our situation, and the excitement we felt in the associated interest of the place, made this one of the most interesting nights I made during our long expedition.