PLATE LXXVII. 



PAGE. 



Fig. 1. DICHOTRYPA FLABELLUM (Eomtnger) 501 



1. The basal portion of a large silicifled example of this species, natural 



size. 



St. Louis group, Spergen Hill, Ind. 

 Illinois State Museum. 

 1 a. Surface of same, x9, showing the usual appearance. 



1 l>. Surface of a better preserved exami le, x9, showing the striate char- 



acter of the interspaces and maculae. 



Fig. 2. DICHOTK YPA LYROIDES Ulr 502 



2. An example of this species showing the thick rounded base. Natural 



size. 



2 a. End view of same. 



St. Louis group, Southern Ky. 

 E. O. [Jlrich's collection. 



2 6. Surface of a well preserved fragment. x9. 



Fig. 3. ACTINOTKYPA pEcuuAKis (Kominger) 503 



8. Surface of a well preserved example, x9, showing arrangement of zooecia 

 apertures and one of the maculae. 



3 a. Small portion of same, xJ8, to show more clearly the tooth-like eleva- 



tions of the internal ridges. 



3 b. Tangential section. x!8 showing characters of the zoarium a short dis- 



tance beneath the surface. 

 Keokuk group, Keokuk, Iowa. 

 E. O. Ulrich's collection. 



Fig. 4. PBISMOPORA TKIFOIJA (Bominger) 505 



4. Small fragment, natural size. This specimen is thinner than usual. 



4 a. About hah* of a more complete and stronger example, natural size. 



The lower portions on the left side represents part of the basal ex- 

 pansion. 

 Keokuk, Iowa. 

 Illinois State Museum. 



4 6. An example of a wider form, differing further from P. trifotia in hav- 

 ing larger cells and the "dimples'' not extending to the margin. 

 Keokuk, Iowa. 

 E. O. Ulrich's collection. 



Fig. 5. MEEKOPOKA APPBOXIMATA Ulr 484 



Surface of the thin bifoliate expansion of a specimen of this species,x9. 

 Chester group, Chester, 111. 

 Illinois State Museum. 



