PLATE XII. 
Callopora cellulosa. 
Page 21. 
See Plates 13 and 23 a. 
Fig - . 1. A frag-ment, natural size, showing- mode of bifurcation and the numerous lateral opening's. 
Lower Helderberg- group. Clarksville, JY. Y. 
Fig. 2. A simple stipe having the openings more regularly arranged. 
Lower Helderberg group. Near Catskill, N. Y. 
Fig. 3. An enlargement of a portion of the preceding. 
Fig. 4. A piece of limestone with a fragment of this species and portions of several other forms. 
Fig. 5. An enlargement of a portion of a branch, showing one of the fistulous openings from which radia¬ 
ting strife extend. 
Fig. 6. A fragment, natural size, showing numerous irregularly arranged openings. 
Figs. 1-6 were originally described as Callopora fistulosa, Hall. (Thirty-second Rept. N. Y. State Mus. 
Nat. Hist., p. 154. 1879.) Subsequent observations have shown that these specimens are 
merely forms of growth of the present species. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 7. Two fragments of branching forms, showing mode of growth, cell apertures, etc. 
Fig. 8. A small branch. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 9. An enlargement from the preceding, showing- the surface characters of the species. 
Callopora perelegans. 
Page 22. 
See Plate 23 a. 
Fig. 10. An irregularly branching specimen, natural size. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 11. A more slender form with numerous branchlets. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 12. A small specimen with branches diverging in several directions, some of which are thickened at 
their extremities. 
Fig. 13. A branching form, similar to, but more slender than the one represented in fig. 11. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 14. A branch, more slender in the central portion, and thickened above from the incipient branching. 
Fig. 15. An enlargement of fig. 10 showing surface characters. 
Fig. 16. A longitudinal section showing cell tubes, their mode of growth and divergence from the axis. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 17. The cell tubes and intermediate cellular interspaces, as seen in a longitudinal translucent section. 
Callopora (Ccelocaulis) IIyale. 
Page 70. 
See Plate 12. 
Fig. 18. An irregularly growing branch which has been partially crushed. 
Fig. 19. An enlargement, showing the surface characters. 
Upper Helderberg group. Onondaga Valley, N. Y. 
Callopora (Ccelocaulis) venusta. 
Page 23. 
See Plate 23 a. 
Fig. 20. A slender branch, natural size. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 21. A larger bifurcating branch. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 22. An enlargement of the preceding, showing the surface characters. 
Fig. 23. An enlargement showing the interior of a bifurcating branch, and a portion of the epitheca. 
Lower Helderberg group. Clarksville, N. Y. 
Fig. 24. A portion of a branch enlarging toward a bifurcation, showing constricted cell apertures, and also 
maculfE without cells. 
Lower Helderberg group. Clarksville, N. Y. 
