Page:Second Geological Survey of Pennsylvania Report of Progress PPP.djvu/16

 them to the genus. Only the separated portions of the trifid rail were then known, and this reference was not unnatural.

1850.—These fragments were ascribed to and constituted as a sub-genus  by Professor McCoy. In the same publication he proposes the genus, and describes two species.

1851.—The following year these species are again described by Prof. McCoy and properly classed with the Phyllopoda, which has since been the receptacle for all fossil forms of a similar nature.

1852.—In 1852, Professor Hall made the first announcement in America of the discovery of fossils similar to those described by Prof. Agassiz as Onchus murchisoni, and described the species Onchus deweyi, from the Niagara group of New York. (Pal. N. Y. Vol. ii, p. 320.)

1853.—M. J. Barrande pointed out the essential identity of the fossils described under the names of and, with the telson and movable spines of , and suggests that these names are superfluous.

Since this time a number of new genera have been established both in America and abroad, of which only those will here be noticed which lead directly to the species of the present paper.

1863.—In the 16th Report of the New York State Cabinet of Natural History, Professor Hall described four species of this order and referred three of them to the genus. Two of these have since been recognized as having been described from different portions of individuals of the same species, and are now united under one species.

1876.—In 1876 the same author again illustrated these species and refered to one as Ceratiocaris (Aristozoe) punctatus, and suggested that the specimens designated as Ceratiocaris armatus were probably identical with it. (Illustrations of Devonian Fossils, pl. 23.)

1879.—Dr. A. S. Packard recognizes the importance of Nebalia and its fossil allies and their relations to the decapods, and proposes the order Phyllocarida for their reception. (Zoölogy American Science Series, p. 703.)