Mr. Asa Gray, professor of botany at Cambridge, near Boston, had offered to accompany me on my journey to Washington. We were to meet at the house of Professor Torrey, at Princeton, a small town half a day's journey from New York, and the seat of a considerable university, one of the oldest in the United States. The physical department, under the direction of Professor Henry, is remarkably rich in models of machinery and in electrical apparatus, to which the professor especially devotes himself. The museum contains a collection of animals and fossil remains. In the environs of the town, in the ditches, is found a rare kind of turtle, remarkable for the form of the jaws and the length of the tail. I wish very much to procure one, were it only to oblige Professor Johannes Muller, of Berlin, who especially desires one for investigation. But I have failed thus far; the turtles are already withdrawn into their winter quarters. Mr. Torrey promises me some, however, in the spring. It is not easy to get them because their bite is dreaded. After this I passed four days in Philadelphia. Here, notwithstanding my great desire to see the beautiful country along the shores of the rich bay of Delaware and the banks of the Schuylkill, between which the city lies, I was entirely occupied with the magnificent collections of the Academy of Science and of the Philosophical Society. The zoological collections of the Academy of Science are the oldest in the United States, the only ones, except those of the Wilkes Expedition, which can equal in interest those of Europe. There are the collections of Say, the earliest naturalist of distinction in the United States; there are also the fossil remains and the animals described by Harlan, by Godman, and by Hayes, and the fossils described by Conrad and Morton. Dr. Morton's unique collection of human skulls is also to be found in Philadelphia. Imagine a series of six hundred skulls, mostly Indian, of all the tribes who now inhabit or formerly inhabited America. Nothing like it exists elsewhere. This collection alone is worth a journey to America. Dr. Morton has had the kindness to give me a copy of his great illustrated work representing all the types of his collection. Quite recently a generous citizen of Philadelphia has enriched this museum with the fine collection of birds belonging to the Duke of Rivoli. He bought it for 37,000 francs, and presented it to his native city. The number of fossil remains comprised in these collections is very considerable; mastodons especially, and fossils of the cretaceous and jurassic deposits. . .Imagine that all this is at my full disposal for description and illustration, and you will understand my pleasure. The liberality of the American naturalists toward me is unparalleled.