The 100 Ám scale bar applies to figs. la,b, 2, 3 and 5;
for figs. 4, 6 and 7, the same scale bar represents 250 (not 100) microns.
Figs. la,b. Spongodrymus elaphococcus. Same specimen, la focussed on the medullary structure, lb focussed on the surface of the cortical shell. IOW 134(F). See also Pl. 29 fig. 3.
Figs. 2, 5-7. Spongosphaera polyacantha, forma streptacantha (figs. 2, 5, 7) and polyacantha. (fig. 6). Fig. 2: "Juvenile" specimen with thin main spines and a rudimentary cortical shell (outine of the shell polygonal and not spherical, as in fully developed shells). Fig. 5: Note the serrate edges of the main spine and the variance in bar thickness, with thin bars in the center and thicker bars near the periphery of the cortical shell. Figs. 7a and 7b focussed on the medullary shells and on the surface of the cortical shell resp.. IOW 134(F), BSS 2813(11 and Spongosphaerid prep. 741 and 696 resp.).
Fig. 3. Spongosphaera spongiosum. BSS 28B (Spongosphaerid prep. 716).
Fig. 4. Spongosphaera leptoplegma. BSS 28B (Spongosphaerid prep. 746).