Plate LIV Continued. 







PAGE. 



Fig. 7. FENESTRAPORA OCCIDENTALS U!r. (See also pi, XLIV) 558 



7. A vertical section through height of branch and keel. x!8. 



7 a. Horizontal section, showing only the keel with three of the shallow 

 cells, x!8. 



7 b. Transverse section of two branches with keels, x!8. 



7 c. Part of a veitical section of the basal portion of the zoarium, x!8. At 

 the upper left hand corner is represented a portion of the outer sub- 

 solid layer. In the lower portion of the figures is shown some loose 

 vesicular tissue which fills the bottom of the infundibular stalk, while 

 the central portion of the figure is occupied by a branch with a num- 

 ber of cells. Between the branch and the outer membrane the space 

 is filled by vesicular tissue. x!8. 



7 d. Horizontal section of the non-celluliferous face, showing large acces- 

 sory cells, and two sets of minute tubuli, xlS. 



7 e. Horizontal section showing the characters of the zoarium at different 

 levels, x!8. 



ttlllft -I'll-.' l.iji! I- :'. ' 



Fig. 8. SEMICOSCINIUM KHOMBICUM TJlr. (See also pi. XLIV) 566 



Horizontal section of an old example, x!8. The half of the figure to the 

 right represents a portion of the section where it passes through the 

 region included between the cell apertures and the tops of the keels. 

 As shown, this region is occupied by irregular vesicles. 

 Hamilton group, Buffalo, Iowa. 



Fig. 9. HEMICOSCINIUM SP. UNDET. 



Transverse section of a branch showing a thin knife-edge keel, x!8. In 

 other species of this genus the keel is expanded or even flattened at 

 the summit. 



Hamilton group, Bake Oven. III. 

 TOi'i^ln: "ih ilJiw u,' . ' ' ' 



Fig. ' 10. HEMITRTPA TENEBA TJlrich. (See also pi. XLIV) 559 



10. Horizontal section, x!8, showing only thu principal bars on the right 

 Hid' 1 , and the secondary bars and scalar of the superficial network on 

 I tHa left side. 



10 a. Horizontal section of the branches, x!8. 



10 6. Vertical section of a branch, x!8; the lorver series of openings repre- 

 sent the zooecia, while the upper series represent the spaces between 

 the columns which support the superficial structure. 

 '"''<$. Transverse section of a branch through one of tin- columns. x!8. 

 Hamilton group, Davenport Iowa. 



OT8 , 



no .baa fJltto lo 'i 



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 liar . 



