588 PROCEEDINGS OF THE NATIONAL MUSEUM. 



acanthopores in this well-developed species of Ilomotrypa is also 

 noteworthy. 



Occurrence. — Not uncommon in the Richmond formation at Wil- 

 mington, Illinois. 



Cat. No. 41761, U.S.N.M. 



EXPLANATION OF PLATES. 



Plate XX. 



Homotriipa dumosn, new species, p. 576. (See also Plate XXI, figs. 1-3.) 



Fig. 1. Tangential section X 35, showing the thin walls, small acanthopores, ano 

 narrow intermural space. 

 Lorraine formation, Covington, Kentucky. 



Rctepora columnifcra Busk, j). 571. 



2. Tangential section of this recent chilostomatous bryozoan, showing structun 



of walls and parenchymal chord. 



Escharopora pavonia (D'Orbigny), p. 571. 



3. Vertical section X 35. 



4. Tangential section X 35. 



Lorraine formation, Cincinnati, Ohio. 



Ceriocava ramosa D'Orbigny, p. 569. 



5, 6. Vertical and tangential sections of this cyclostomatous bryozoan, showin 

 vesicles supposed to be homologous with the cystiphragms. ( After Ulrich. 

 Cretaceous of France. 



Homotriipa grandis, new species, p. 578. 



7. Tangential section X 20. 



8. A^ertical section X 20, showing only a portion of the axial and peripheri 



regions. 



9. Tangential section X 50 of a single zooecium. 



10. Natural-size view of a fragment of a zoarium. 



Lorraine formation, Lumsleys Fork, 2 miles west of Goodlettsville, Davidso 

 County, Tennessee. 



Homolrypa jmlchra, new species, p. 577. 



11. Vertical section X 20, showing the distribution of diaphragms and cyst 



phragms. 

 12, 13. Tangential section X 20, and a small portion of same X 50. 



14. A small but nearly complete zoarium, natural size. 

 Lorraine formation, Cincinnati, Ohio. 



Homolrypa nitida, new species, p. 586. (See also Plate XXV, figs. 5-8.) 



15. Tangential section of several zooecia X 40. 

 Richmond formation, near Osgood, Indiana. 



