visiting Hawaii when overcame him in 1902. It it very unfortunate that he never fully wrote out the results of his studies upon these shells, the manuscript which was found after his death being very incomplete, especially upon specific points, and although many of his descriptions of the species themselves were completed, yet his conclusions respecting their relationship and migrations are only vaguely referred to. He did, however, published a short paper in Science in 1898 in which he finds that there are about 280 species of land snails on the island of Oahu, with three leading genera, Bulimella, Achatinella and Apex. All of these are probably descended from the recently extinct Achatinella phæzona of Kiliouou valley, whenc they migrated northward, and are now found chiefly on the western sides of the range of mountains which extends along the eastern shore of the island.
Only a very few Achatinella crossed the broad lowlands in the middle of the island, and reached the range along the western coast. Species of Apex,however, crossed these lowlands and now thrive on the western range, but do not live well on the seaward face of either the eastern or the western range of the mountains. but have not crossed the lowlands,and are not found on the western range of the mountains. Hyatt saw that the Achatinellidæ of the Hawaiian Islands afforded a preeminently favorable opportunity for the study of the effects of physical conditions on structure. He knew the stock from which he could trace the migrations of the various descendant races, and he became familiar with the different physical surroundings to the effects of which these races were subjected. Thus he felt that he could demonstrate conclusively the effects of environment upon the structure of the shells, and perhaps upon the soft parts of the animals. This research would, had he completed it, have been his masterpiece, and would have added greatly to the world's store of knowledge.
In 1888 Hyatt published in the Proceedings of the Boston Society of Natural History, his final paper upon the "Larval Theory of the Origin of Cellular Tissues," in which he maintains that the metazoa are descended from colonial forms of protozoa, and the metazoa may be regarded as complexes of multicellular colonies in which growth by sexual union and resulting fission of the ovum leads to the formation of three primary body layers enclosing an archeteron. Volvox or Eudorina are forms intermediate between metazoa and protozoa, and may be called mesozoa, being multicellular colonies composed of only one layer of closely connected cells forming a primitive tissue.
Hyatt's scientific papers and published discussions cover a wide range of subjects and include such titles as the temperature of caves and wells; the absence of distinct marks of glaciation in Alaska; rock ruins at Niagar Falls; the chasms of the Colorado; a disintegrating