Two years later his marriage to Elizabeth Cabot Cary of Boston bound him still closer to the land of his adoption, and the remaining years of his life were years of consistent activity filled with growth and honor. An expedition to Lake Superior in 1848 was followed by a trip to study the Florida reefs in 1850 and a visit to the Mississippi River in 1853. During these years his collections were rapidly increased, and already he was planning for the establishment at Harvard of a great Museum of Natural History. Life in Boston and in the clear atmosphere of the University must have been highly stimulating to a man of Agassiz’s sensitive susceptibilities. Emerson, Holmes, Hawthorne, Motley, and Longfellow were his companions, and a group of brilliant younger minds surrounded him in his work. From abroad now came honors the larger part of which Agassiz saw fit to decline. In 1852 the Prix Cuvier was awarded to him in recognition of his work on fossil fishes. A call to the University of Zürich was declined in 1854; and during the four years between 1857 and 1861 he three times declined a call to the chair of palæontology at Paris, perhaps the highest scientific honor which the world could afford. But neither honors nor wealth could tempt him. His affection for America and his love for his work in that appreciative country held him fast. In 1861 he became a naturalized citizen of the United States. Rarely, if ever, was there a man of more lovable and winning personality. “Everybody sought his society, and no one could stand before his words and his smile. The fishermen at Nahant would pull two or three miles to get him a rare fish.” Rich and poor, the educated and the uneducated, all paid homage to his magnetic personality. Physically large, his genial countenance and smiling eyes made friends with everyone. And at the same time those laughing brown eyes, that seemed made only for pleasure and jollity, “saw more than did all our eyes put together; for he looked, but we only stared.”