At Washington are also to be seen the headquarters of the Coast Survey, where the fine charts of the coasts and harbors now making under direction of Dr. Bache are executed. These charts are admirably finished. Dr. Bache, the superintendent, was in camp, so that I could not deliver my letters for him. I saw, however, Colonel Abert, the head of the topographic office, who gave me important information about the West for the very season when I am likely to be there. I am indebted to him also for a series of documents concerning the upper Missouri and Mississippi, California and Oregon, printed by order of the government, and for a collection of fresh-water shells from those regions. I should like to offer him, in return, such sheets of the Federal Map as have appeared. I beg Guyot to send them to me by the first occasion. As I was due in Boston on an appointed day I was obliged to defer my visit to Richmond, Charleston, and other places in the South. I had, beside, gathered so much material that I had need of a few quiet weeks to consider and digest it all. Returning therefore to Philadelphia, I made there the acquaintance of Mr. Haldeman, author of a monograph on the fresh-water shells of the United States. I had made an appointment to meet him at Philadelphia, being unable to make a detour of fifty leagues in order to visit him at his own home, which is situated beyond the lines of rapid transit. He is a distinguished naturalist, equally well versed in several branches of our science. He has made me acquainted, also, with a young naturalist from the interior of Pennsylvania, Mr. Baird, professor at Dickinson College, in Carlisle, Pennsylvania, who offered me duplicates from his collections of birds and other animals. In order to avail myself more promptly of this and like acquisitions, I wish that M. Coulon would send me at the close of the winter all that he can procure of the common European birds, of our small mammalia, and some chamois skins, adding also the fish that Charles put aside for me before his departure. It would be safest to send them to the care of Auguste Mayor. At Philadelphia I separated from my traveling companion, Mr. Gray, who was obliged to return to his home. From Philadelphia, Mr. Haldeman and Mr. Lea accompanied me to Bristol, where Mr. Vanuxem possesses an important collection of fossils from ancient deposits, duplicates of which he promises me. Mr. Vanuxem is one of the official geologists of the State of New York, and author of one of a series of volumes upon the geology of the State, about which I shall presently have something to say. To gain time I took the night train from Bristol to New York, and arrived at Mayor's at midnight, having written him to expect me.