ABSTRACT
Knowledge of the brachyurans of the Neotropical Region steadily progressed through the efforts of pre-Linnean naturalists, the French entomologists, and many other 18th and 19th century taxonomists, helped by a host of often forgotten collectors. This chapter is devoted to diseases and other medical topics, was written by Piso. The oxystomatous crabs from two expeditions, including six new species, were dealt with by Rathbun and included in her last monograph. In her monograph she illustrated first male gonopods of 17 pseudothelphusids; however, she ignored the gonopod in describing the remainder of pseudothelphusids and in describing all trichodactylids. After her mongraph, Rathbun described nine additional pseudothelphusids; six of these are considered valid today. The Thayer Expedition, one of the main sources of freshwater crabs for Rathbun's monograph, was led by Louis Agassiz and named after Nathaniel Thayer, a friend of Agassiz and a trustee of the Harvard Museum, who covered the expenses.
