PalcBOzoic Corals of the State of Ohio. 95 



EXPLANATION OF PLATE V. 



[All the figures of this plate, except figs. 15 and 15 a, are highly mag- 

 nified ; but they are not uniformly enlarged ; and, for the sake of clearness, 

 they are rendered very slightly diagrammatic, though at the same time 

 they are faithful representations of the objects drawn.] 



Fiff. 1. Portion of a ci'oss section of Chcstetes rhomhtcus, Nich., showing 

 part of the outer margin and part of the central area ; 1 a, a few 

 cells from the central portion of the same, still more highly 

 magnified, showing the peculiar divisional lines in the calcite 

 filling the tubes ; 1 b, long section of part of a branch of the 

 same. 



Fig. 2. Longitudinal section of part of a branch of Chcetetes siffiUarioides, 

 Nich., showing the minutely tabulate interstitial tubuli. 



Fig. 3. Longitudinal section of part of a branch of Chcetetes nodulosus, 

 Nich. 



Fig. 4. Longitudinal section of part of a branch of Chatetes rugosuSf 

 Edw. & Haime. 



Fig. 5. Longitudinal section of part of a branch of Chcetetes Jamesi, Nich. 



Fig. 6. Vertical section of part of a small example of Chcetetes petro- 

 politanus, Pander ; 6 a, portion of a horizontal section of the 

 same specimen. 



Fig. 7. Part of a horizontal section of Chcetetes discoid^us, James, close 

 to the centre of the corallum j 7 a, portion of a vertical section 

 of the same. 



Fig. 8. Part of a horizontal section of Chcetetes Newherryi, Nich. ; 8 a, part 

 of a vertical section of the same. 



Fig. 9. Part of a horizontal section of Chcetetes clathratulus, James ; 

 9 a, part of a vertical section of the same. On one side a second 

 layer of short corallites is seen to be superimposed on the two 

 original layers forming the corallum. 



Fig. 10. Part of a transverse section of Co)istellaria antheloidea, Hall, 

 showing a portion of the margin and a portion of the central 

 region ; 10 a, part of a vertical section of another example of 

 the same. 



Fig. 11. Part of a horizontal section of Chcetetes frondosus, D'Orb. (?) ; 

 though essentially parallel to the surface, the section has divided 

 the corallites in a slightly oblique manner ; 11 «, part of a vertical 

 section of another example of the same. 



Fig. 12. Part of a horizontal section of a branch oiDekayia attrita, Nich., 

 taken from the central region of the branch, and showing the 

 surface-columns cut across transversely ; 12 a, part of a vertical 

 section of another example of the same, showing the longitu- 

 dinally divided columns as thickenings of the walls of the 

 corallites. 



Fig. 13. Portion of a vertical section of a branch of Chcetetes gracilis, 

 James. 



Fig. 14. Portion of a transverse section of a branch of Chcetetes Fletchei'i, 

 Edw. & Haime, showing part of the margin and part of the 

 central area. 



Figs, 15 & 15 a. Transverse and vertical sections of Streptelasma corni- 

 culwn, Hall. 



(All the specimens figured are from the Cincinnati Group of Ohio, with 

 the exception of the specimens of C. petropolitanus figui'ed in 6 and 6 a, 

 which are from the Trenton Limestone of Canada.) 



