PLATE XL 



PAGE 



Figs. 1-4. ORTHOCERAS TELAMON Hall (?) 311 



1. Internal impression of living chamber. 



2. Septum of preceding, showing excentric siphuncle. 



3. A specimen showing five air-chambers. 



4. Septum of preceding, showing excentric siphuncle. 



Romney formation, Hamilton member, Robinsons farm, 2 

 miles south of Patterson Depot, W. Va. 



Figs. 5, 6. OKTHOCERAS TELAMON Hall .". 311 



5. Small fragment showing depth of air-chambers and gradual en- 



largement of tube. 



6. A septum, showing very excentric position of siphuncle. 



Hamilton formation, New York. 



Fig. 7. ORTHOCERAS EMACERATUM Hall (?) 313 



Internal impression, showing six air-chambers. Romney formation, 

 Hamilton member, right bank of Potomac, 3 miles below Cum- 

 berland. 



Fig. 8. ORTHOCERAS CF. ATJLAX Hall 313 



Portion of living chamber, showing surface markings. Romney forma- 

 tion, Hamilton member, road east of Pine Hill, about 4 miles 

 north of Oldtown. 



Fig. 9. ORTHOCERAS AULAX Hall 313 



Fragment of living chamber, showing the prominent, regular trans- 

 verse furrows and ridges of the surface. Hamilton formation, 

 New York. 



123 





