The collection consists of 32 letters written by Samuel L. Clemens to Mary Benjamin Rogers (Mrs. H.H.), his niece by marriage, and four letters written to Clemens and forwarded by him to Mrs. Rogers with comments. The letters are very personal in tone, full of Clemens' well-known wit, and revealing of his personal characteristics. There are a few clippings, cartoons, and one photograph. Also, a collection of 18 letters written by Clemens to Dorothy Sturgis, 1908-1909, relating to the "Angel-Fish Aquarium." There is also one typescript of the Constitution of the Club"The Aquarium, Issued by the Admiral;" and a photograph album of the Mark Twain Dinner, 1905.