Page:The Habitat of the Eurypterida.djvu/27

 undetermined Pterygotus mentioned by Billings, is from the Grand Greve limestone of Lower Devonic age. Remains of Pterygotus have also been found in the lower marine Devonic at Dalhousie. Finally, near Campbellton, New Brunswick, "in some indurated limestones containing fish remains of probably Upper Devonic age" are also eurypterid remains which Clarke and Ruedemann have described as Pterygotus atlanticus. An extremely incomplete and problematic form is a two-jointed fragment from the lower beds of the Portage sandstones of Italy, Yates County, New York. Originally described by Dawson as a plant (Equisetides wrightiana Dawson), it was later placed among the eurypterids by Hall as Stylonurus (?) wrightiana and is now so recognized by Clarke and Ruedemann. There is but a single fragment, part of a jointed appendage apparently. A number of fragments of Stylonurus, originally described as Stylonurus excelsior by Hall and which Beecher used in making the restoration which he called Stylonurus lacoanus, have all been united by Clarke and Ruedemann under the species Stylonurus (Ctenopterus) excelsior. There are only two specimens, one a complete carapace from the Catskill beds at Andes, Delaware County, New York, and another more fragmentary carapace from the same formation in Pennsylvania. Eurypterus beecheri Hall described from the Chemung of Pennsylvania has proved to be the same as Stylonurus beecheri.

. From the Waverly beds of Warren, Warren County, Pennsylvania, a single eurypterid was described by Hall and Clarke in 1888 as Eurypteris approximatus. No complete description of this form is given anywhere, but the figure in the Palaeontology of New York, Volume VII, plate 27, figure 6, (106), shows the one specimen that has been found in which there are the cephalon and nine somites. This form is regarded by Clarke and Ruedemann as one of several phylogerontic species of Eurypterus which constitute the end members in different lines of development in North America and mark the decline of the race.

. In the Carbonic (Pennsylvanic) are found four species of Eurypterus in Pennsylvania; Eurypterus (Anthraconectes) mazonensis Meek and Worthen (170) in the Coal Measures of Mazon Creek, Ill.; two species in the Carbonic of Nebraska, and two doubtful species from St. John, New Brunswick. Particular attention should be called to Eurypterus (Anthraconectes) mansfieldi which C. E. Hall has figured (98, pl. IV), showing the form just as it was found lying on ferns in a very perfect state of preservation, in the lower Productive