PLATE XXXIII 



PACK 



Figs. 1-3. OPHILETA COMPACTA Salter 304 



I, 2. Lower and upper sides of a specimen. 



3. Schematic cross-section of the same. 



Ordovician (Canadian), Beekmantown Is., Beekmantown, 

 New York. 



Figs. 4, 5. SYNTKOPHIA LATERALIS Whitfield 267 



4. Pedicle valve. X 2. 



5. Sketch of hinge of same. 



Ordovician (Canadian), Kittatinny Is., Columbia, New 

 Jersey. 



Figs. 6, 7. ECCUOPTERUS TRIANGULUS (Whitfield) 302 



6. 7. Top and side views of a cast of the interior. 



Ordovician (Canadian), Beekmantown Is., Providence Island, 

 Vermont. 



Figs. 8, 9. MACLUKITES AFFINIS (Billings) 297 



8. Top view. 



9. Cross-section of the shell. 



Ordovician (Canadian), Division F of Quebec group. Keppel 

 Island, Newfoundland. 



Figs. 10-12. HYSTBICURUS CONICUS (Billings) 340 



10. Glabella. X 2. 



II. Pygidium. X 2. 



12 Profile of glabella in outline. 



Ordovician (Canadian), Beekmantown Is., Beekmantown, 

 New York. 



Figs. 13-15. TETRADIUM SIMPLEX Bassler n. sp 199 



13. Weathered fragment of limestone showing edge view of tubes. 



14. Top view of corallum. 



15. Portion of same. X 4. 



Ordovician (Canadian), lower part of the Beekmantown Is. 

 just above the Stonehenge member, eastern edge of Hagerstown, 

 Maryland. 



Figs. 1-3, 10-12 are after Whitfield; 4, 5, after Weller; 6, 7, 

 after Ulrich; and 8 and 9 after Billings. 



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