PLATE XLVII 



PAGE 



Figs. 1-3. SCENIDIUM ANTHONENSE Sardeson 268 



1. A complete brachial valve. X 2. 



2. Incomplete pedicle valve. X 2. 



3. Profile of same. X 2. 



Ordovician (Mohawkian), Black River portion of the Jackson- 

 burg Is., Jacksonburg, New Jersey. 



Figs. 4-6. ORTHIS TBICENABIA Conrad 240 



Brachial and pedicle valves of a complete example and profile view of 

 same. 



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

 Minneapolis, Minnesota. 



Figs. 7, 8. PRASOPORA CONTIGUA Ulrich 216 



7. Tangential section of the hemispheric zoarium, showing the com- 



parative fewness of mesopores. X 16. 



8. Vertical section illustrating the occurrence of cystiphragms and 



also the small number of mesopores. X 18. 



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

 Goodhue County, Minnesota. 



Figs. 9-11. DIPLOTRYPA ? APPALACHIA Bassler n. sp 219 



9. View of the hemispheric zoarium, basal side up in the rock. 



10. Tangential section. X 10. 



11. Vertical section. X 10. 



Ordovician (Mohawkian), Nidulites bed of Chambersburg Is., 

 Strasburg, Virginia. 



Figs. 12-14. CORYNOTRYPA DELicATULA ( James) 213 



12. Zoarium illustrating the elongate club-shaped, incrusting zocecia. 



X 9. 



13. Several zocecia of the same zoarium more slender than usual. X 25. 



14. Unusually large zocecia of another form of the species. X 25. 



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

 St. Paul, Minnesota. 



Figs. 15-17. CORYNOTRYPA INFLATA (Hall) 212 



15. Small portion of a large zoarium growing upon a brachiopod. X 9. 



16. Three zocecia of one form of the species. X 18. 



17. Profile view of a zocecium. 



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

 Cannon Falls, Minnesota. 



Fig. 18. ONCHOMETOPUS SIMPLEX Raymond and Narraway 348 



An imperfect specimen referred to the species on account of its general 

 form but particularly on account of the absence of a concave 

 border. 



Ordovician (Mohawkian), Nidulites bed of Chambersburg Is., 

 Wilson, Maryland. 



Figs. 1-3 are after Weller; 4-6 are after Winchell and 

 Schuchert; 7, 8, 12-17 after Ulrich. 



397 



