I wish to express my thanks to Dr. R. Ruedemann, who allowed me to study the large collection of New York eurypterids at the State Museum in Albany; to Dr. C. D. Walcott, who showed me the large Beltina fauna and the beautiful specimens of Limulava from the Middle Cambric Stephen shale of Canada in the Smithsonian Institution at Washington, D. C; and to Mr. McIntosh at the Museum of the Natural History Society, St. John, New Brunswick, for information about the age of the Little River Plant beds and for the privilege of being allowed to inspect the type material from those beds.
To the courtesy and helpfulness of Mr. Henry R. Howland, Superintendent of the Buffalo Society of Natural Sciences, I owe the opportunity of studying every specimen of eurypterid in the museum of that Society. Furthermore, Mr. Howland loaned me a number of specimens to describe, and I was thus able to show the existence of two species of a pulmonale gastropod, Hercynella, in the Bertie waterlime. It was because of Mr. Howland's interest in papers dealing with the geological problems of the Buffalo region that the present contribution appears in the Bulletin of the Buffalo Society of Natural Sciences.
With the fullest appreciation for the inspiration and guidance which I have received, I gladly acknowledge my indebtedness to Professor Amadeus W. Grabau. He was one of the first to advocate the fluviatile habitat of the eurypterids and one of my earliest geological recollections was of a discussion between him and a number of men who argued for the marine habitat, a discussion to which I listened with the utmost interest although I was then not in a position to weigh the evidence brought forward on either side. More than four years ago Professor Grabau suggested that I take up the problem, with the purpose of marshalling all of the available evidence in proof of an hypothesis which he had strong theoretic reasons for believing to be true. Throughout the work I have profitted by the helpful criticisms and keen suggestions of a man who has made such problems his specialty for twenty-five years, and without whose assistance this paper certainly could not have been written. The method of treatment which I have used is based upon the principles of interpretational geology expounded in the Palaeontological Laboratory of Columbia University, and with the hope that this paper shall not prove unworthy of the teachings there set forth, I informally dedicate it to the American School of Philosophic Geologists, among the leaders of whom Professor Grabau stands so preëminent.
