Letter from Timothy Abbott Conrad concerning fossil and shell specimens, the geological age of Canada shells, number of extinct shells in fluviatile deposits, number of freshwater shells in Middle and Lower Tertiary strata and the localities of tertiary strata and their fossils, February 1840;
Letter describing a voyage to the Gulf of Mexico where he made observations on fossil shells and rock types of the Florida Keys, Tampa Bay and the Mississippi River, 17 October 1845;
Letter concerning fossils. He has compared a new shell to Erycinella Ovalis and believes them to be the same species despite slight differences, he has found 2 examples of a new Avicula and a new Dentalium and 2 other new fossils, he has been promised a collection of large bones recently dug up in Georgia which he believes to be Megatherium. He also mentions the Visksburg fossils, 24 November 1852;
Letter principally concerning the Greenwich bone and marl, near Greenwich which Conrad believes is of the Miocene epoch, he lists species of shell common to Europe and Texas, 28 July 1853;
Letter concerning marl from the Miocene and Cretaceous periods and specimens he has found near the village of Jericho and Mullica Hill in New Jersey which include a vertebral joint of Prisco-Delfphinus and a tooth of Crocodilus Antiquus found in the Miocene marl near Jericho. He states that Leidy will send him a copy of his paper on the Burlington tooth, 12 August 1853.