CRUSTACEA. 



85 



No entire specimen of l.his species — "the largest trilobite by far," says Hall, 

 "which occurs in the higher rocks of our system" — has ever been found. 

 From the Upper Helderberg Group (Devonian), Genesee Co., N. Y. 



Size, 9x8. 



No. 153. [410, Cast]. Dalmania nasutus, Conrad. 



Buckler. From the Low^er Helderberg (Upper 

 Silurian) in Schoharie County, N. Y. 



Size. 7 X 6. 



No. 154. [412, Cast]. Dalmania naSUtUS, Conrad. 



Pygidiijm, with spine; impression and relief. From the 

 same locality as the preceding. 



No. 155. [405, Cast]. Dalmania (Cryphaeus) calliteles, Green. 



Pygidium, showing the lobes more deeply cleft than in the 

 preceding species. From the Hamilton Group, York, N. Y. 



No. 156. [416, Cast]. Dikelocephalus Minnesotensis, Owen. 



Central portion of the head with cheek, placed on 

 the same slab with tail. The body segments are want- 

 ing in this specimen, and portions of the cheeks and 

 tail are restored. This is one of the earliest of the 

 Trilobite forms. From the Potsdam Sandstone (Lower 

 Silurian), Maozmania, Wisconsin. 



Size, 9x8. 



No. 157. Elipsocephalus Hoffii, Schlotheim. 

 From Lower Silurian, at Ginetz, Bohemia. 



