

PLATK LVII. 



fill I)/ PAGB. 



Fig. 1. HEMITRTPA PROUTASA Ulr 560 



1. Celluliferous surface, with superficial net work. x9. 



1 a. Non-celluliferous surface of an average example. x9. 



1 b. Vertical section of branch ami superficial network, x!8. Slightly oblique. 



1 c. Transverse section of several branches and superficial network, x!8. 



The branch on the right is about to bifurcate. 

 Warsaw be Is, Warsaw, 111. 

 E. O. Ulrich's collection. 



.O'MHiM'Xl-f lo -jrajy -isi* luuijRK .f 

 Fig. 2. HEMITRTPA PHOUTANA var. NODULOSA Ulr i'l.-ii.!Jiu..-i.., <v.Ui 562 



2. Superficial net-work. x9, showing the floriform interstice. 



2 a. Celluliferous face of branches, x9. 



2 6. Non-collullferous face of branches, x9, showing the small nodes, and 



the relative size of branches and fenestrules. 

 2 c. Thin section showing structure of zoarium just beneath the zooocia.xlS. 



Keokuk group, Keokuk, Iowa. 



E. O. Ulrich's collection. 



Fig. 3. HEMITBYP A NODOSA Ulr 562 



3. Non-celluliferous face of branches, x9. showing nodose character of 



branches. 



Keokuk group. Bentonsport. Iowa. 



Illinois State Museum. 



Fig. 3 a. HEMITRTPA ASPERA ? Ulr 563 



Portion of the reverse ofa frond where the nodes are on the branches 



instead of the dissepiments, x9. On other parts they occupy the usual 



position. 



Keokuk group, Nauvoo, III. 



E. O. Ulrich's co'lection. 



Fig. 4. HEMITEYPA ASPERA Ulr 563 



4. The reverse aspect of the basal portion of a frond. Natural size. 



4 a. Obverse side of same, x9, showing the character of the superficial net- 

 work. 



4 6. Reverse side of same, x9, showing the thick branches and dissepi- 

 ments and the subcircular fenestrules. 

 Keokuk group, Beutonsport, Iowa. 

 Illinois State Museum. 



4 c. Superficial net-work of another example. 

 Keokuk group. Nauvoo, 111. 

 E. O. Ulrich's collection. 



4 d. Non-celluliferous side of same, x9. 



4 e and 4/. Thin sections showing structure of the cortical or reverse side 

 of the branches, x!8. 



