on my return to the river I passed a creek about 20 yds. wide near it's entrance it had a handsome little stream of runing water;  in this creek I saw several softshelled Turtles which were the first that have been seen this season; this I believe proceeded reather from the season than from their non existence in the portion of the river from the Mandans hither.    on the Stard. shore I killed a fat buffaloe which was very acceptable to us at this moment; the party came up to me late in the evening and encamped for the night on the Lard. side.    it was after dark before we finished butchering the buffaloe, and on my return to camp I trod within five inches of a rattle snake but being in motion I passed before he could probably put himself in a striking attitude and fortunately escaped his bite, I struck about at random [lying] with my espontoon being directed in some measure by his nois untill I killed him. Our hunters had killed two of the Bighorned Anamals since I had left them.  

Excerpt taken from online journals at http://lewisandclarkjournals.unl.edu.