Page:The Habitat of the Eurypterida.djvu/58



From 1818 when the first Eurypterus was discovered in America by Dr. S. L. Mitchell until 1900, the order of the Eurypterida was held to be made up of marine organisms. This belief in the marine habitat of the oldest Arthropoda known suddenly became the centre of contention at the beginning of the present century in spite of its long period of security. As soon as geologists considered the possibility of origins other than marine for conglomerates, shales and even limestones, there arose discussion as to the nature of the beds in which eurypterids had been found and opinions were perceived to be divergent. It is of interest, then, to take up a systematic review of the literature for the last hundred years and to note what has been the general opinion of geologists and palaeontologists about the