PLATE XLI 



PAGE 



Figs. 1-3. SOLENOPOBA coMPACTA Billings 192 



1. View of a small mass. 



2, 3. Longitudinal and transverse sections. X 35. 



Ordovician (Mohawkian), Black River (Decorah) shales, near 

 Cannon Falls, Minnesota. 



Fig. 4. TETRADIUM COLUMNABE (Hall) 201 



Fragment of a corallum. 



Ordovician (Mohawkian), Trenton Is., Lewis County, New 

 York. 



Fig. 5. COLUMNARIA HALLi Nicholson 198 



Corallum showing the little extension of the septa in the tubes. 

 Ordovician (Mohawkian), Trenton Is. of Canada. 



Fig. 6. HEBERTELLA BELLARUGOSA (Conrad) 239 



Exterior of a brachial valve. 



Ordovician (Mohawkian), Trenton shales of Minnesota. 



Fig. 7. CABYOCYSTITES sp 208 



A weathered plate of this cystid showing the pores. X 4. 



Ordovician, Caryocystites bed of the Chambersburg Is., Fort 

 London, Pennsylvania. 



Figs. 8, 9. RAFINESQUINA CHAMPLAINENSIS Raymond 261 



8. Specimen exhibiting brachial valve, cardinal area, and deltidium. 



9. Pedicle valve. 



Ordovician (Chazyan), New York. 



Fig. 10. CARABOCBINXJS sp 209 



An imperfect plate. 



Ordovician, Caryocystites bed of Chambersburg Is., Fort 

 London, Pennsylvania. 



Figs. 11-13. LEPTAENA CHABLOTTAE Winchell and Schuchert 257 



Views of the pedicle and brachial valve and side outline of the same 

 specimen. 



Ordovician (Mohawkian), Black River (Decorah) shales, 

 St. Paul, Minnesota. 



Figs. 14-16. CAMABOTOECHIA PLENA (Hall) 270 



Views of the pedicle and brachial valves and side outline of an average 

 specimen. 

 Ordovician (Chazyan), Canada. 



Fig. 17. HEBEBTELLA BOBEALIS (Billings) 238 



An example showing the pedicle valve. 



Ordovician (Chazyan), near Montreal, Canada. 



Fig. 18. HEBEBTELLA VULGABIS Raymond 239 



Pedicle valve of a large example. X 2. 



Ordovician (Chazyan), New York. 



Fig. 19. GONIOCEBAS CHAZIENSE Ruedemann 328 



An imperfect specimen showing the arrangement of the septa. 



Ordovician, Carocystites bed of the Chambersburg Is., Fort 

 Loudon, Pennsylvania. 



Figs. 1-3, 6, 11-13, are after Winchell and Schuchert; 4 after 

 Hall; 5, 14-16, after Billings; and 8, 9, 17, 18, after Raymond. 



sn 



