PLATE IV. 



Brooksella alternata (p. 23). 



Figs. 1, 2, 3, 4, 5. Transverse sections showing in natural colors the various forms of the lobes, and 



the color of the inclosing matrix. 

 Fig. 6. Transverse sections of an individual in which various interradial lobes are cut across. 

 Figs. 7, 8, 9. Transverse sections in which the radial canals of the exumbrella lobes and the central 



stomach of the umbrella disk are preserved. This is particularly well shown in fig. 9. 

 Figs. 10, 10a, 11, 11a. Vertical sections in which the radial canals and the lobes of the umbrella are 



shown. Figs. 10 and 11 show the iimbrella disk; 10, toward the margin ; and 11, nearer 



the center. In figs. 10a and 11a the openings of the radial canals and the sections of the 



umbrella lobes are clearly shown. 

 Fig. 13. Vertical section through the center of another individual which cuts through the depth of 



the umbrella lobes on each side. The umbrella disk is outlined below and the radial 



canals above. 

 Fig. 13. Section showing same essential features as fig. 10a. 

 Fig. 14. Vertical section cutting across several interradial lobes or arms. 

 Fig. 15. Vertical central section showing traces of the umbrella disk. 



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