NO. 5 ORDOVICIAN BRYOZOA — BOARDMAN 2.^ 



acanthopores, and monticules in lower right and middle left of figure 

 that are convex enough to project the offset acanthopores into the 

 plane of the section. 

 Fig. 2e. Longitudinal section of lectotype, X 20, showing a well-developed 

 zonation of offset acanthopores through the middle of the exozone. 



Plate 6 



Amplexopora scptosa (Ulrich) 



Fig. la. Longitudinal view of paratype, U.S.N.M. 138284, X 100, showing 

 zooecial wall structure with thin zooecial lining connected directly to 

 the thicker diaphragms. Extreme proximal (left side of figure) 

 diaphragms in both zooecia are compound. 



Fig. lb. Longitudinal view of same specimen, X 20, showing an extreme de- 

 velopment of irregularly and closely spaced cystoidal and compound 

 diaphragms. Note offsetting of exozone of monticule in left center 

 of figure. 



Fig. ic. Tangential view of same variant specimen, X 50, showing acanthopores 

 between zooecial corners that cause little offset and inflection of 

 zooecial walls. Other zooecia in the section show the stronger, more 

 typical inflection. 



Fig. 2. Longitudinal view of topotype, U.S.N.M. 138288, X 50. showing ap- 

 pearance of a moderate development of offset acanthopores. From 

 topotype suite of U.S.N.M. 44913. 



Fig. 3a. Longitudinal view of paratype, U.S.N.M. 138287, X So, showing a 

 young growth stage indicated by few zooecial diaphragms and 

 mesopore with early chambers beaded. 



Fig. 3b. Longitudinal view of same specimen, X 100, showing zooecial wall 

 structure with sharply defined zooecial boundaries of abutting laminae. 



Fig. 3c. Tangential view of same specimen, X 5o, showing severe inflection of 

 zooecial walls by spinelike acanthopores equal in development to those 

 shown in longitudinal view in plate 5, figure 2c. 



Plate 7 

 Fig. I. Aniplexopora rmriabile (Ulrich) 



Fig. la. Longitudinal view of lectotype, U.S.N.M. 43820, X 20, from the top 



of the Richmond group, Osgood, Ind. 

 Fig. lb. Tangential view of same specimen, X 20, showing small acanthopores 



confined to zooecial corners. 



Fig. 2. Batostoma implicatum (Nicholson) 



Longitudinal view of identified specimen, U.S.N.M. 138269, X 50, showing the 

 appearance of a thin-walled essentially incrusting growth, comparable in 

 dimensions to longitudinal views of B. ovata. Note location of incrusting 

 growth in larger view of section, plate i, figure 4. U.S.N.M. collection 2995- 



Fig. 3. Batostoma ovata (Ulrich) 



Fig. 3a. Longitudinal view of lectotype, U.S.N.M. 138289, X SO, showing thin, 

 remote zooecial diaphragms, a sharply defined zooecial boundary, and 



