PALEOZOIC TIME — UPPER SILURIAN. 



557 



Other genera of Eurypterids have their species in the Water-lime. One 

 from Kokomo, Indiana, Carcinosoma ingens of Clay pole (1894), had a length 

 of 24 inches. In Pterygotus, which is one of them, 

 there are chelate antennae at the front margin, and 799. 



the caudal segment is broad. In P. acuticaudatus 

 of Pohlman, from near Buffalo, the telson alone is 

 6k inches long. 



Crustaceans of the genus Ceratiocaris occur in 

 the same beds. 



Arachnids represented by Scorpions. — The 



American Scorpion of the Water-lime is from 

 beds at Waterville, JST.Y. It is represented in 

 Mg. 799, from a paper by R. P. Whitfield (1885). 



Vertebrates. — Remains of Placoderm Fishes, 

 related to the Pteraspids (page 566), occur in the 

 upper portion of the Onondaga beds of middle 

 Pennsylvania, and have been described by E. W. 

 Claypole (1884, 1892). Fig. 800 represents two 

 imperfect plates, which are supposed to be parts 

 of dorsal and ventral shields ; Figs. 801, 802, side 

 views of a dorsal plate, showing also the lateral 

 plate ; Fig. 803, a pectoral fin ; and 804, a restora- 

 tion, giving the supposed form of the Fish. 



The few fossils of the Onondaga beds, which occur in 

 the non-saliferous portion, exclusive of the Tentaculite 

 limestone, include the following : — 



Orhiculoidea Vanuxemi H., Meristella sulcata Van., Leperditia alta Con., species of 



Proscorpius Osborni (x 2). 

 Whitfield. 



800 



800-804. 



Placodebm. — Palaeaspis Americana: Fig. 800, two plates, supposed to be part of ventral and dorsal, in po- 

 sition; 801, 802, side view of dorsal plate, with the lateral plate; 803, pectoral fin ; 804, restoration, giving 

 probable form (all x |). Claypole. 



Enryptenis, Pterygotus, Eusarcus, Dolichopterus, Ceratiocaris (4: sp.), Tentaculites gyra- 



